How do I remove a property from a JavaScript object

Question

Say I create an object as follows  let myObject        quot ircEvent quot    quot PRIVMSG quot      quot method quot    quot newURI quot      quot regex quot    quot  http      quot      What is the best way to remove the property regex to end up with new myObject as follows  let myObject        quot ircEvent quot    quot PRIVMSG quot      quot method quot    quot newURI quot

User · Answer

Objects in JavaScript can be thought of as maps between keys and values. The delete operator is used to remove these keys, more commonly known as object properties, one at a time.

_x000D_

var obj = {_x000D_
  myProperty: 1    _x000D_
}_x000D_
console.log(obj.hasOwnProperty('myProperty')) // true_x000D_
delete obj.myProperty_x000D_
console.log(obj.hasOwnProperty('myProperty')) // false

_x000D_

The delete operator does not directly free memory, and it differs from simply assigning the value of null or undefined to a property, in that the property itself is removed from the object. Note that if the value of a deleted property was a reference type (an object), and another part of your program still holds a reference to that object, then that object will, of course, not be garbage collected until all references to it have disappeared.

delete will only work on properties whose descriptor marks them as configurable.

User · Answer

To remove a property from an object  mutating the object   you can do it like this  delete myObject regex     or  delete myObject  regex       or  var prop    quot regex quot   delete myObject prop    Demo  x000D   x000D  var myObject          ircEvent    PRIVMSG        method    newURI        regex     http          delete myObject regex   console log myObject   x000D   x000D   x000D   For anyone interested in reading more about it  Stack Overflow user kangax has written an incredibly in-depth blog post about the delete statement on their blog  Understanding delete  It is highly recommended  If you d like a new object with all the keys of the original except some  you could use the destructuring  Demo  x000D   x000D  let myObject        ircEvent    PRIVMSG      method    newURI      regex     http           const  regex     newObj    myObject   console log newObj        has no  regex  key console log myObject      remains unchanged x000D   x000D   x000D

User · Answer

Two ways to delete an object  using for in function deleteUser key      const newUsers         for  const uid in users           if  uid     key           newUsers uid    users uid       return newUsers      or delete users key

User · Answer

To remove a property from an object  mutating the object   you can do it like this  delete myObject regex     or  delete myObject  regex       or  var prop    quot regex quot   delete myObject prop    Demo  x000D   x000D  var myObject          ircEvent    PRIVMSG        method    newURI        regex     http          delete myObject regex   console log myObject   x000D   x000D   x000D   For anyone interested in reading more about it  Stack Overflow user kangax has written an incredibly in-depth blog post about the delete statement on their blog  Understanding delete  It is highly recommended  If you d like a new object with all the keys of the original except some  you could use the destructuring  Demo  x000D   x000D  let myObject        ircEvent    PRIVMSG      method    newURI      regex     http           const  regex     newObj    myObject   console log newObj        has no  regex  key console log myObject      remains unchanged x000D   x000D   x000D

User · Answer

There are a lot of good answers here but I just want to chime in that when using delete to remove a property in JavaScript  it is often wise to first check if that property exists to prevent errors   E g  var obj     property   value    property2   value     if  obj  amp  amp  obj hasOwnProperty  property2        delete obj property2    else       error handling     Due to the dynamic nature of JavaScript there are often cases where you simply don t know if the property exists or not  Checking if obj exists before the  amp  amp  also makes sure you don t throw an error due to calling the hasOwnProperty   function on an undefined object   Sorry if this didn t add to your specific use case but I believe this to be a good design to adapt when managing objects and their properties

User · Answer

Spread Syntax  ES6   To whoever needs it     To complete  Koen answer in this thread  in case you want to remove dynamic variable using the spread syntax  you can do it like so    x000D   x000D  const key    a   x000D           x000D  const    key   foo     rest       a  1  b  2  c  3    x000D   x000D  console log foo       1 x000D  console log rest        b  2  c  3   x000D   x000D   x000D      foo will be a new variable with the value of a  which is 1     EXTENDED ANSWER  There are few common ways to remove a property from an object Each one has it s own pros and cons  check this performance comparison    Delete Operator Readable and short  however  it might not be the best choice if you are operating on a large number of objects as its performance is not optimized   delete obj key      Reassignment More than 2X faster than delete  however the property is not deleted and can be iterated   obj key    null  obj key    false  obj key    undefined     Spread Operator This ES6 operator allows us to return a brand new object  excluding any properties  without mutating the existing object  The downside is that it has the worse performance out of the above and not suggested to be used when you need to remove many properties at a time      key   val     rest     obj

User · Answer

Suppose you have an object that looks like this   var Hogwarts         staff              Argus Filch            Filius Flitwick            Gilderoy Lockhart            Minerva McGonagall            Poppy Pomfrey                          students              Hannah Abbott            Katie Bell            Susan Bones            Terry Boot            Lavender Brown                          Deleting an object property  If you want to use the entire staff array  the proper way to do this  would be to do this   delete Hogwarts staff    Alternatively  you could also do this   delete Hogwarts  staff      Similarly  removing the entire students array would be done by calling delete Hogwarts students  or delete Hogwarts  students      Deleting an array index  Now  if you want to remove a single staff member or student  the procedure is a bit different  because both properties are arrays themselves   If you know the index of your staff member  you could simply do this   Hogwarts staff splice 3  1     If you do not know the index  you ll also have to do an index search   Hogwarts staff splice Hogwarts staff indexOf  Minerva McGonnagall   - 1  1       Note  While you technically can use delete for an array  using it would result in getting incorrect results when calling for example Hogwarts staff length later on  In other words  delete would remove the element  but it wouldn t update the value of length property  Using delete would also mess up your indexing   So  when deleting values from an object  always first consider whether you re dealing with object properties or whether you re dealing with array values  and choose the appropriate strategy based on that   If you want to experiment with this  you can use this Fiddle as a starting point

User · Answer

Another solution  using Array reduce    x000D   x000D  var myObject     x000D     ircEvent    PRIVMSG   x000D     method    newURI   x000D     regex     http       x000D     x000D   x000D  myObject   Object keys myObject  reduce function obj  key    x000D    if  key     regex                 key you want to remove x000D      obj key    myObject key   x000D      x000D    return obj  x000D          x000D   x000D  console log myObject   x000D   x000D   x000D    However  it will mutate the original object  If you want to create a new object without the specified key  just assign the reduce function to a new variable  e g      ES6    x000D   x000D  const myObject     x000D    ircEvent   PRIVMSG   x000D    method   newURI   x000D    regex    http        x000D     x000D   x000D  const myNewObject   Object keys myObject  reduce  obj  key    gt    x000D    key      regex    obj key    myObject key    null  x000D    return obj  x000D          x000D   x000D  console log myNewObject   x000D   x000D   x000D

User · Answer

Using lodash  import omit from  lodash omit    const prevObject    test  false  test2  true      Removes test2 key from previous object const nextObject   omit prevObject   test2      Using Ramda  R omit   a    d     a  1  b  2  c  3  d  4        gt   b  2  c  3

User · Answer

This post is very old and I find it very helpful so I decided to share the unset function I wrote in case someone else see this post and think why it s not so simple as it in PHP unset function  The reason for writing this new unset function  is to keep the index of all other variables in this hash map  Look at the following example  and see how the index of  quot test2 quot  did not change after removing a value from the hash map   x000D   x000D  function unset unsetKey  unsetArr  resort      var tempArr   unsetArr    var unsetArr         delete tempArr unsetKey     if  resort        j   -1        for  i in tempArr        if  typeof tempArr i        undefined           if  resort            j            else           j   i                unsetArr j    tempArr i               return unsetArr     var unsetArr     test    deletedString    test2     console log unset  1   unsetArr  true       output Object  0   test   1   test2   console log unset  1   unsetArr  false       output Object  0   test   2   test2   x000D   x000D   x000D

User · Answer

I personally use Underscore js or Lodash for object and array manipulation   myObject     omit myObject   regex

User · Answer

To remove a property from an object  mutating the object   you can do it like this  delete myObject regex     or  delete myObject  regex       or  var prop    quot regex quot   delete myObject prop    Demo  x000D   x000D  var myObject          ircEvent    PRIVMSG        method    newURI        regex     http          delete myObject regex   console log myObject   x000D   x000D   x000D   For anyone interested in reading more about it  Stack Overflow user kangax has written an incredibly in-depth blog post about the delete statement on their blog  Understanding delete  It is highly recommended  If you d like a new object with all the keys of the original except some  you could use the destructuring  Demo  x000D   x000D  let myObject        ircEvent    PRIVMSG      method    newURI      regex     http           const  regex     newObj    myObject   console log newObj        has no  regex  key console log myObject      remains unchanged x000D   x000D   x000D

User · Answer

x000D   x000D  let myObject          ircEvent    PRIVMSG        method    newURI        regex     http            obj   Object fromEntries      Object entries myObject  filter function  m           return m 0      regex   or whatever key to delete             console log obj  x000D   x000D   x000D   You can also just treat the object like a2d array using Object entries  and use splice to remove an element as you would in a normal array  or simply filter through the object  as one would an array  and assign the reconstructed object back to the original variable

User · Answer

x000D   x000D  var myObject     ircEvent    PRIVMSG    method    newURI    regex     http         x000D       x000D  delete myObject regex  x000D   x000D  console log   myObject regex      logs  undefined x000D   x000D   x000D    This works in Firefox and Internet nbsp Explorer  and I think it works in all others

User · Answer

Object assign    amp  Object keys    amp  Array map     x000D   x000D  const obj     x000D       Filters    x000D            x000D               FilterType   between   x000D               Field   BasicInformationRow A0   x000D               MaxValue   2017-10-01   x000D               MinValue   2017-09-01   x000D               Value   Filters value  x000D            x000D        x000D     x000D   x000D  let new obj1   Object assign     obj Filters 0    x000D  let new obj2   Object assign     obj Filters 0    x000D   x000D     x000D   x000D     old version x000D   x000D  let shaped obj1   Object keys new obj1  map  x000D       key  index    gt    x000D          switch  key    x000D              case  MaxValue   x000D                  delete new obj1  MaxValue    x000D                  break  x000D              case  MinValue   x000D                  delete new obj1  MinValue    x000D                  break  x000D            x000D          return new obj1  x000D        x000D    0   x000D   x000D   x000D  let shaped obj2   Object keys new obj2  map  x000D       key  index    gt    x000D          if key      Value    x000D              delete new obj2  Value    x000D            x000D          return new obj2  x000D        x000D    0   x000D   x000D   x000D     x000D   x000D   x000D     new version  x000D   x000D  let shaped obj1   Object keys new obj1  forEach  x000D       key  index    gt    x000D          switch  key    x000D              case  MaxValue   x000D                  delete new obj1  MaxValue    x000D                  break  x000D              case  MinValue   x000D                  delete new obj1  MinValue    x000D                  break  x000D              default  x000D                  break  x000D            x000D        x000D     x000D   x000D  let shaped obj2   Object keys new obj2  forEach  x000D       key  index    gt    x000D          if key      Value    x000D              delete new obj2  Value    x000D            x000D        x000D     x000D   x000D   x000D

User · Answer

x000D   x000D  var myObject     ircEvent    PRIVMSG    method    newURI    regex     http         x000D       x000D  delete myObject regex  x000D   x000D  console log   myObject regex      logs  undefined x000D   x000D   x000D    This works in Firefox and Internet nbsp Explorer  and I think it works in all others

User · Answer

If you don t want to modify the original object  Remove a property without mutating the object If mutability is a concern  you can create a completely new object by copying all the properties from the old  except the one you want to remove   x000D   x000D  let myObject        ircEvent    PRIVMSG      method    newURI      regex     http           let prop    regex   const updatedObject   Object keys myObject  reduce  object  key    gt      if  key     prop        object key    myObject key        return object         console log updatedObject   x000D   x000D   x000D

User · Answer

This post is very old and I find it very helpful so I decided to share the unset function I wrote in case someone else see this post and think why it s not so simple as it in PHP unset function  The reason for writing this new unset function  is to keep the index of all other variables in this hash map  Look at the following example  and see how the index of  quot test2 quot  did not change after removing a value from the hash map   x000D   x000D  function unset unsetKey  unsetArr  resort      var tempArr   unsetArr    var unsetArr         delete tempArr unsetKey     if  resort        j   -1        for  i in tempArr        if  typeof tempArr i        undefined           if  resort            j            else           j   i                unsetArr j    tempArr i               return unsetArr     var unsetArr     test    deletedString    test2     console log unset  1   unsetArr  true       output Object  0   test   1   test2   console log unset  1   unsetArr  false       output Object  0   test   2   test2   x000D   x000D   x000D

User · Answer

Using ramda dissoc you will get a new object without the attribute regex   const newObject   R dissoc  regex   myObject      newObject     myObject   You can also use other functions to achieve the same effect - omit  pick

User · Answer

ECMAScript 2015  or ES6  came with built-in Reflect object  It is possible to delete object property by calling Reflect deleteProperty   function with target object and property key as parameters   Reflect deleteProperty myJSONObject   regex      which is equivalent to   delete myJSONObject  regex      But if the property of the object is not configurable it cannot be deleted neither with deleteProperty function nor delete operator   let obj   Object freeze   prop   value      let success   Reflect deleteProperty obj   prop    console log success      false console log obj prop      value   Object freeze   makes all properties of object not configurable  besides other things   deleteProperty function  as well as delete operator  returns false when tries to delete any of it s properties  If property is configurable it returns true  even if property does not exist   The difference between delete and deleteProperty is when using strict mode    use strict    let obj   Object freeze   prop   value      Reflect deleteProperty obj   prop       false delete obj  prop       TypeError  property  prop  is non-configurable and can t be deleted

User · Answer

I personally use Underscore js or Lodash for object and array manipulation   myObject     omit myObject   regex

User · Answer

johnstock  we can also use JavaScript s prototyping concept to add method to objects to delete any passed key available in calling object  Above answers are appreciated   x000D   x000D  var myObject        ircEvent    PRIVMSG      method    newURI      regex     http              1st and direct way  delete myObject regex     delete myObject  regex   console log myObject        ircEvent   PRIVMSG   method   newURI        2 way -  by using the concept of JavaScript s prototyping concept Object prototype removeFromObjectByKey   function key         If key exists  remove it and return true   if  this key      undefined        delete this key      return true           Else return false   return false     var isRemoved   myObject removeFromObjectByKey  method   console log myObject       ircEvent   PRIVMSG        More examples var obj       a  45    b  56    c  67   console log obj       a  45  b  56  c  67       Remove key  a  from obj isRemoved   obj removeFromObjectByKey  a   console log isRemoved     true console log obj        b  56  c  67       Remove key  d  from obj which doesn t exist var isRemoved   obj removeFromObjectByKey  d   console log isRemoved      false console log obj        b  56  c  67   x000D   x000D   x000D

User · Answer

Old question  modern answer  Using object destructuring  an ECMAScript nbsp 6 feature  it s as simple as   const   a     rest       a  1  b  2  c  3      Or with the questions sample   const myObject     ircEvent    PRIVMSG    method    newURI    regex     http         const   regex     newObject     myObject  console log newObject     You can see it in action in the Babel try-out editor     Edit   To reassign to the same variable  use a let   let myObject     ircEvent    PRIVMSG    method    newURI    regex     http            regex     myObject     myObject   console log myObject

User · Answer

Spread Syntax  ES6   To whoever needs it     To complete  Koen answer in this thread  in case you want to remove dynamic variable using the spread syntax  you can do it like so    x000D   x000D  const key    a   x000D           x000D  const    key   foo     rest       a  1  b  2  c  3    x000D   x000D  console log foo       1 x000D  console log rest        b  2  c  3   x000D   x000D   x000D      foo will be a new variable with the value of a  which is 1     EXTENDED ANSWER  There are few common ways to remove a property from an object Each one has it s own pros and cons  check this performance comparison    Delete Operator Readable and short  however  it might not be the best choice if you are operating on a large number of objects as its performance is not optimized   delete obj key      Reassignment More than 2X faster than delete  however the property is not deleted and can be iterated   obj key    null  obj key    false  obj key    undefined     Spread Operator This ES6 operator allows us to return a brand new object  excluding any properties  without mutating the existing object  The downside is that it has the worse performance out of the above and not suggested to be used when you need to remove many properties at a time      key   val     rest     obj

User · Answer

johnstock  we can also use JavaScript s prototyping concept to add method to objects to delete any passed key available in calling object  Above answers are appreciated   x000D   x000D  var myObject        ircEvent    PRIVMSG      method    newURI      regex     http              1st and direct way  delete myObject regex     delete myObject  regex   console log myObject        ircEvent   PRIVMSG   method   newURI        2 way -  by using the concept of JavaScript s prototyping concept Object prototype removeFromObjectByKey   function key         If key exists  remove it and return true   if  this key      undefined        delete this key      return true           Else return false   return false     var isRemoved   myObject removeFromObjectByKey  method   console log myObject       ircEvent   PRIVMSG        More examples var obj       a  45    b  56    c  67   console log obj       a  45  b  56  c  67       Remove key  a  from obj isRemoved   obj removeFromObjectByKey  a   console log isRemoved     true console log obj        b  56  c  67       Remove key  d  from obj which doesn t exist var isRemoved   obj removeFromObjectByKey  d   console log isRemoved      false console log obj        b  56  c  67   x000D   x000D   x000D

User · Answer

Using delete method is the best way to do that  as per MDN description  the delete operator removes a property from an object  So you can simply write   delete myObject regex     OR delete myObject  regex         The delete operator removes a given property from an object  On   successful deletion  it will return true  else false will be returned    However  it is important to consider the following scenarios          If the property which you are trying to delete does not exist  delete   will not have any effect and will return true   If a property with the same name exists on the object s prototype   chain  then  after deletion  the object will use the property from the   prototype chain  in other words  delete only has an effect on own   properties     Any property declared with var cannot be deleted from the global scope   or from a function s scope    As such  delete cannot delete any functions in the global scope  whether this is part from a function definition or a function   expression      Functions which are part of an object  apart from the   global scope  can be deleted with delete    Any property declared with let or const cannot be deleted from the scope  within which they were defined  Non-configurable properties cannot be removed  This includes properties of built-in objects like Math  Array  Object and properties that are created as non-configurable with methods like Object defineProperty         The following snippet gives another simple example    x000D   x000D  var Employee     x000D        age  28  x000D        name   Alireza   x000D        designation   developer  x000D        x000D       x000D      console log delete Employee name        returns true x000D      console log delete Employee age         returns true x000D       x000D         When trying to delete a property that does  x000D         not exist  true is returned  x000D      console log delete Employee salary      returns true x000D   x000D   x000D    For more info about and seeing more example  visit the link below   https   developer mozilla org en-US docs Web JavaScript Reference Operators delete

User · Answer

Another alternative is to use the Underscore js library    Note that   pick   and   omit   both return a copy of the object and don t directly modify the original object  Assigning the result to the original object should do the trick  not shown    Reference  link   pick object   keys   Return a copy of the object  filtered to only have values for the  whitelisted keys  or array of valid keys    var myJSONObject      ircEvent    PRIVMSG    method    newURI    regex     http            pick myJSONObject   ircEvent    method      gt    ircEvent    PRIVMSG    method    newURI      Reference  link   omit object   keys   Return a copy of the object  filtered to omit the  blacklisted keys  or array of keys    var myJSONObject      ircEvent    PRIVMSG    method    newURI    regex     http            omit myJSONObject   regex      gt    ircEvent    PRIVMSG    method    newURI      For arrays    filter   and   reject   can be used in a similar manner

User · Answer

Another solution  using Array reduce    x000D   x000D  var myObject     x000D     ircEvent    PRIVMSG   x000D     method    newURI   x000D     regex     http       x000D     x000D   x000D  myObject   Object keys myObject  reduce function obj  key    x000D    if  key     regex                 key you want to remove x000D      obj key    myObject key   x000D      x000D    return obj  x000D          x000D   x000D  console log myObject   x000D   x000D   x000D    However  it will mutate the original object  If you want to create a new object without the specified key  just assign the reduce function to a new variable  e g      ES6    x000D   x000D  const myObject     x000D    ircEvent   PRIVMSG   x000D    method   newURI   x000D    regex    http        x000D     x000D   x000D  const myNewObject   Object keys myObject  reduce  obj  key    gt    x000D    key      regex    obj key    myObject key    null  x000D    return obj  x000D          x000D   x000D  console log myNewObject   x000D   x000D   x000D

User · Answer

The term you have used in your question title Remove a property from a JavaScript object  can be interpreted in some different ways  The one is to remove it for whole the memory and the list of object keys or the other is just to remove it from your object  As it has been mentioned in some other answers  the delete keyword is the main part  Let s say you have your object like   myJSONObject     ircEvent    PRIVMSG    method    newURI    regex     http           If you do   console log Object keys myJSONObject      the result would be     ircEvent    method    regex     You can delete that specific key from your object keys like   delete myJSONObject  regex      Then your objects key using Object keys myJSONObject  would be     ircEvent    method     But the point is if you care about memory and you want to whole the object gets removed from the memory  it is recommended to set it to null before you delete the key   myJSONObject  regex     null  delete myJSONObject  regex      The other important point here is to be careful about your other references to the same object  For instance  if you create a variable like   var regex   myJSONObject  regex      Or add it as a new pointer to another object like   var myOtherObject       myOtherObject  regex     myJSONObject  regex      Then even if you remove it from your object myJSONObject  that specific object won t get deleted from the memory  since the regex variable and myOtherObject  regex   still have their values  Then how could we remove the object from the memory for sure   The answer would be to delete all the references you have in your code  pointed to that very object and also not use var statements to create new references to that object  This last point regarding var statements  is one of the most crucial issues that we are usually faced with  because using var statements would prevent the created object from getting removed   Which means in this case you won t be able to remove that object because you have created the regex variable via a var statement  and if you do   delete regex    False   The result would be false  which means that your delete statement haven t been executed as you expected  But if you had not created that variable before  and you only had myOtherObject  regex   as your last existing reference  you could have done this just by removing it like   myOtherObject  regex     null  delete myOtherObject  regex      In other words  a JavaScript object gets killed as soon as there is no reference left in your code pointed to that object     Update  Thanks to  AgentME      Setting a property to null before deleting it doesn t accomplish   anything  unless the object has been sealed by Object seal and the   delete fails  That s not usually the case unless you specifically   try     To get more info on Object seal  Object seal

User · Answer

You can use filter like below  x000D   x000D  var myObject          ircEvent    PRIVMSG        method    newURI        regex     http              way 1  let filter1        Object keys     myObject   filter d   gt      if d      regex        filter1 d    myObject d           console log filter1      way 2  let filter2   Object fromEntries Object entries     myObject   filter d   gt   d 0       regex      console log filter2  x000D   x000D   x000D

User · Answer

Using delete method is the best way to do that  as per MDN description  the delete operator removes a property from an object  So you can simply write   delete myObject regex     OR delete myObject  regex         The delete operator removes a given property from an object  On   successful deletion  it will return true  else false will be returned    However  it is important to consider the following scenarios          If the property which you are trying to delete does not exist  delete   will not have any effect and will return true   If a property with the same name exists on the object s prototype   chain  then  after deletion  the object will use the property from the   prototype chain  in other words  delete only has an effect on own   properties     Any property declared with var cannot be deleted from the global scope   or from a function s scope    As such  delete cannot delete any functions in the global scope  whether this is part from a function definition or a function   expression      Functions which are part of an object  apart from the   global scope  can be deleted with delete    Any property declared with let or const cannot be deleted from the scope  within which they were defined  Non-configurable properties cannot be removed  This includes properties of built-in objects like Math  Array  Object and properties that are created as non-configurable with methods like Object defineProperty         The following snippet gives another simple example    x000D   x000D  var Employee     x000D        age  28  x000D        name   Alireza   x000D        designation   developer  x000D        x000D       x000D      console log delete Employee name        returns true x000D      console log delete Employee age         returns true x000D       x000D         When trying to delete a property that does  x000D         not exist  true is returned  x000D      console log delete Employee salary      returns true x000D   x000D   x000D    For more info about and seeing more example  visit the link below   https   developer mozilla org en-US docs Web JavaScript Reference Operators delete

User · Answer

Using lodash  import omit from  lodash omit    const prevObject    test  false  test2  true      Removes test2 key from previous object const nextObject   omit prevObject   test2      Using Ramda  R omit   a    d     a  1  b  2  c  3  d  4        gt   b  2  c  3

User · Answer

Another alternative is to use the Underscore js library    Note that   pick   and   omit   both return a copy of the object and don t directly modify the original object  Assigning the result to the original object should do the trick  not shown    Reference  link   pick object   keys   Return a copy of the object  filtered to only have values for the  whitelisted keys  or array of valid keys    var myJSONObject      ircEvent    PRIVMSG    method    newURI    regex     http            pick myJSONObject   ircEvent    method      gt    ircEvent    PRIVMSG    method    newURI      Reference  link   omit object   keys   Return a copy of the object  filtered to omit the  blacklisted keys  or array of keys    var myJSONObject      ircEvent    PRIVMSG    method    newURI    regex     http            omit myJSONObject   regex      gt    ircEvent    PRIVMSG    method    newURI      For arrays    filter   and   reject   can be used in a similar manner

User · Answer

Objects in JavaScript can be thought of as maps between keys and values. The delete operator is used to remove these keys, more commonly known as object properties, one at a time.

_x000D_

var obj = {_x000D_
  myProperty: 1    _x000D_
}_x000D_
console.log(obj.hasOwnProperty('myProperty')) // true_x000D_
delete obj.myProperty_x000D_
console.log(obj.hasOwnProperty('myProperty')) // false

_x000D_

The delete operator does not directly free memory, and it differs from simply assigning the value of null or undefined to a property, in that the property itself is removed from the object. Note that if the value of a deleted property was a reference type (an object), and another part of your program still holds a reference to that object, then that object will, of course, not be garbage collected until all references to it have disappeared.

delete will only work on properties whose descriptor marks them as configurable.

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If you want to delete a property deeply nested in the object then you can use the following recursive function with path to the property as the second argument   var deepObjectRemove   function obj  path to key       if path to key length     1           delete obj path to key 0            return true       else          if obj path to key 0                return deepObjectRemove obj path to key 0    path to key slice 1            else             return false             Example    var a         level1           level2               level3                    level4   yolo                                    deepObjectRemove a    level1    level2    level3     console log a      Prints  level1   level2

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The obvious way to remove a property from an object is to use the delete keyword  this can be done like this  delete myObject  regex    or this  delete myObject regex  If you are cocerned with mutability  you can create a new object by copying all the properties from the old  except the one you would like to remove let myObject        ircEvent   quot PRIVMSG quot      method   quot newURI quot      regex   quot  http      quot      const propertyToRemove    regex  const newObject   Object keys myObject  reduce  object  key    gt       if  key     propertyToRemove           object key    car key       return object

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Suppose you have an object that looks like this   var Hogwarts         staff              Argus Filch            Filius Flitwick            Gilderoy Lockhart            Minerva McGonagall            Poppy Pomfrey                          students              Hannah Abbott            Katie Bell            Susan Bones            Terry Boot            Lavender Brown                          Deleting an object property  If you want to use the entire staff array  the proper way to do this  would be to do this   delete Hogwarts staff    Alternatively  you could also do this   delete Hogwarts  staff      Similarly  removing the entire students array would be done by calling delete Hogwarts students  or delete Hogwarts  students      Deleting an array index  Now  if you want to remove a single staff member or student  the procedure is a bit different  because both properties are arrays themselves   If you know the index of your staff member  you could simply do this   Hogwarts staff splice 3  1     If you do not know the index  you ll also have to do an index search   Hogwarts staff splice Hogwarts staff indexOf  Minerva McGonnagall   - 1  1       Note  While you technically can use delete for an array  using it would result in getting incorrect results when calling for example Hogwarts staff length later on  In other words  delete would remove the element  but it wouldn t update the value of length property  Using delete would also mess up your indexing   So  when deleting values from an object  always first consider whether you re dealing with object properties or whether you re dealing with array values  and choose the appropriate strategy based on that   If you want to experiment with this  you can use this Fiddle as a starting point

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To clone object without property  For example  let object     a  1  b  2  c  3        And we need to delete a   With explicit prop key       const   a     rest     object      object   rest    With variable prop key       const propKey    a       const    propKey   propValue     rest     object      object   rest    Cool arrow function        const removeProperty    propKey     propKey   propValue     rest      gt  rest       object   removeProperty  a   object     For multiple properties      const removeProperties    object     keys    gt  Object entries object  reduce  prev   key  value     gt       prev       keys includes key   amp  amp     key   value             Usage object   removeProperties object   a    b      result   gt    c  3    Or     const propsToRemove     a    b       object   removeProperties object     propsToRemove     result   gt    c  3

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Property Removal in JavaScript  There are many different options presented on this page  not because most of the options are wrong   or because the answers are duplicates   but because the appropriate technique depends on the situation you re in and the goals of the tasks you and or you team are trying to fulfill  To answer you question unequivocally  one needs to know    The version of ECMAScript you re targeting The range of object types you want to remove properties on and the type of property names you need to be able to omit  Strings only  Symbols  Weak references mapped from arbitrary objects  These have all been types of property pointers in JavaScript for years now  The programming ethos patterns you and your team use  Do you favor functional approaches and mutation is verboten on your team  or do you employ wild west mutative object-oriented techniques  Are you looking to achieve this in pure JavaScript or are you willing  amp  able to use a 3rd-party library    Once those four queries have been answered  there are essentially four categories of  property removal  in JavaScript to chose from in order to meet your goals  They are   Mutative object property deletion  unsafe  This category is for operating on object literals or object instances when you want to retain continue to use the original reference and aren t using stateless functional principles in your code  An example piece of syntax in this category    use strict  const iLikeMutatingStuffDontI     myNameIs   KIDDDDD     Symbol for  amICool     true   delete iLikeMutatingStuffDontI Symbol for  amICool       true Object defineProperty   myNameIs   KIDDDDD     amICool     value  true  configurable  false    delete iLikeMutatingStuffDontI  amICool      throws   This category is the oldest  most straightforward  amp  most widely supported category of property removal  It supports Symbol  amp  array indexes in addition to strings and works in every version of JavaScript except for the very first release  However  it s mutative which violates some programming principles and has performance implications  It also can result in uncaught exceptions when used on non-configurable properties in strict mode   Rest-based string property omission  This category is for operating on plain object or array instances in newer ECMAScript flavors when a non-mutative approach is desired and you don t need to account for Symbol keys   const foo     name   KIDDDDD     Symbol for  isCool     true   const   name     coolio     foo    coolio doesn t have  name  const   isCool     coolio2     foo    coolio2 has everything from  foo  because  isCool  doesn t account for Symbols      Mutative object property deletion  safe  This category is for operating on object literals or object instances when you want to retain continue to use the original reference while guarding against exceptions being thrown on unconfigurable properties    use strict  const iLikeMutatingStuffDontI     myNameIs   KIDDDDD     Symbol for  amICool     true   Reflect deleteProperty iLikeMutatingStuffDontI  Symbol for  amICool       true Object defineProperty   myNameIs   KIDDDDD     amICool     value  true  configurable  false    Reflect deleteProperty iLikeMutatingStuffDontI   amICool      false   In addition  while mutating objects in-place isn t stateless  you can use the functional nature of Reflect deleteProperty to do partial application and other functional techniques that aren t possible with delete statements   Syntax-based string property omission  This category is for operating on plain object or array instances in newer ECMAScript flavors when a non-mutative approach is desired and you don t need to account for Symbol keys   const foo     name   KIDDDDD     Symbol for  isCool     true   const   name     coolio     foo    coolio doesn t have  name  const   isCool     coolio2     foo    coolio2 has everything from  foo  because  isCool  doesn t account for Symbols      Library-based property omission  This category is generally allows for greater functional flexibility  including accounting for Symbols  amp  omitting more than one property in one statement   const o   require  lodash omit   const foo      Symbol for  a      abc   b   b   c   c    const bar   o foo   a        a  undefined  const baz   o foo    Symbol for  a     b        Symbol supported  more than one prop at a time   Symbol for  a   undefined

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ECMAScript 2015  or ES6  came with built-in Reflect object  It is possible to delete object property by calling Reflect deleteProperty   function with target object and property key as parameters   Reflect deleteProperty myJSONObject   regex      which is equivalent to   delete myJSONObject  regex      But if the property of the object is not configurable it cannot be deleted neither with deleteProperty function nor delete operator   let obj   Object freeze   prop   value      let success   Reflect deleteProperty obj   prop    console log success      false console log obj prop      value   Object freeze   makes all properties of object not configurable  besides other things   deleteProperty function  as well as delete operator  returns false when tries to delete any of it s properties  If property is configurable it returns true  even if property does not exist   The difference between delete and deleteProperty is when using strict mode    use strict    let obj   Object freeze   prop   value      Reflect deleteProperty obj   prop       false delete obj  prop       TypeError  property  prop  is non-configurable and can t be deleted

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To clone object without property  For example  let object     a  1  b  2  c  3        And we need to delete a   With explicit prop key       const   a     rest     object      object   rest    With variable prop key       const propKey    a       const    propKey   propValue     rest     object      object   rest    Cool arrow function        const removeProperty    propKey     propKey   propValue     rest      gt  rest       object   removeProperty  a   object     For multiple properties      const removeProperties    object     keys    gt  Object entries object  reduce  prev   key  value     gt       prev       keys includes key   amp  amp     key   value             Usage object   removeProperties object   a    b      result   gt    c  3    Or     const propsToRemove     a    b       object   removeProperties object     propsToRemove     result   gt    c  3

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Dan s assertion that  delete  is very slow and the benchmark he posted were doubted  So I carried out the test myself in Chrome 59  It does seem that  delete  is about 30 times slower   var iterationsTotal   10000000      10 million var o  var t1   Date now   t2  for  let i 0  i lt iterationsTotal  i         o    a 1 b 2 c 3 d 4 e 5      delete o a  delete o b  delete o c  delete o d  delete o e    console log   t2 Date now   -t1       6135 for  let i 0  i lt iterationsTotal  i         o    a 1 b 2 c 3 d 4 e 5      o a   o b   o c   o d   o e   undefined    console log  Date now  -t2       205   Note that I purposedly carried out more than one  delete  operations in one loop cycle to minimize the effect caused by the other operations

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To remove a property from an object  mutating the object   you can do it like this  delete myObject regex     or  delete myObject  regex       or  var prop    quot regex quot   delete myObject prop    Demo  x000D   x000D  var myObject          ircEvent    PRIVMSG        method    newURI        regex     http          delete myObject regex   console log myObject   x000D   x000D   x000D   For anyone interested in reading more about it  Stack Overflow user kangax has written an incredibly in-depth blog post about the delete statement on their blog  Understanding delete  It is highly recommended  If you d like a new object with all the keys of the original except some  you could use the destructuring  Demo  x000D   x000D  let myObject        ircEvent    PRIVMSG      method    newURI      regex     http           const  regex     newObj    myObject   console log newObj        has no  regex  key console log myObject      remains unchanged x000D   x000D   x000D

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x000D   x000D  let myObject          ircEvent    PRIVMSG        method    newURI        regex     http            obj   Object fromEntries      Object entries myObject  filter function  m           return m 0      regex   or whatever key to delete             console log obj  x000D   x000D   x000D   You can also just treat the object like a2d array using Object entries  and use splice to remove an element as you would in a normal array  or simply filter through the object  as one would an array  and assign the reconstructed object back to the original variable

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I have used lodash  unset  to make it happen for nested object also   only this need to write small logic to get path of property key which expected by omit method      Method which returns property path as array     x000D   x000D  var a     bool    must     range    price index final price    gt   450   lt   500       bool    should     term    color value keyword   Black           x000D   x000D  function getPathOfKey object key currentPath  t   x000D       var currentPath   currentPath        x000D   x000D      for var i in object   x000D    if i    key   x000D          t   currentPath  x000D          x000D        else if typeof object i      object    x000D          currentPath push i  x000D         return getPathOfKey object i   key currentPath  x000D          x000D        x000D   t push key   x000D      return t  x000D    x000D  document getElementById  output   innerHTML  JSON stringify getPathOfKey a  price index final price    x000D   lt div id  output  gt   x000D   x000D   lt  div gt  x000D   x000D   x000D     Then just using lodash unset method remove property from object      x000D   x000D  var unset   require  lodash unset    x000D  unset a getPathOfKey a  price index final price     x000D   x000D   x000D

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x000D   x000D  var myObject     ircEvent    PRIVMSG    method    newURI    regex     http         x000D       x000D  delete myObject regex  x000D   x000D  console log   myObject regex      logs  undefined x000D   x000D   x000D    This works in Firefox and Internet nbsp Explorer  and I think it works in all others

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Object assign    amp  Object keys    amp  Array map     x000D   x000D  const obj     x000D       Filters    x000D            x000D               FilterType   between   x000D               Field   BasicInformationRow A0   x000D               MaxValue   2017-10-01   x000D               MinValue   2017-09-01   x000D               Value   Filters value  x000D            x000D        x000D     x000D   x000D  let new obj1   Object assign     obj Filters 0    x000D  let new obj2   Object assign     obj Filters 0    x000D   x000D     x000D   x000D     old version x000D   x000D  let shaped obj1   Object keys new obj1  map  x000D       key  index    gt    x000D          switch  key    x000D              case  MaxValue   x000D                  delete new obj1  MaxValue    x000D                  break  x000D              case  MinValue   x000D                  delete new obj1  MinValue    x000D                  break  x000D            x000D          return new obj1  x000D        x000D    0   x000D   x000D   x000D  let shaped obj2   Object keys new obj2  map  x000D       key  index    gt    x000D          if key      Value    x000D              delete new obj2  Value    x000D            x000D          return new obj2  x000D        x000D    0   x000D   x000D   x000D     x000D   x000D   x000D     new version  x000D   x000D  let shaped obj1   Object keys new obj1  forEach  x000D       key  index    gt    x000D          switch  key    x000D              case  MaxValue   x000D                  delete new obj1  MaxValue    x000D                  break  x000D              case  MinValue   x000D                  delete new obj1  MinValue    x000D                  break  x000D              default  x000D                  break  x000D            x000D        x000D     x000D   x000D  let shaped obj2   Object keys new obj2  forEach  x000D       key  index    gt    x000D          if key      Value    x000D              delete new obj2  Value    x000D            x000D        x000D     x000D   x000D   x000D

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Try the following method  Assign the Object property value to undefined  Then stringify the object and parse    x000D   x000D   var myObject     ircEvent    PRIVMSG    method    newURI    regex     http         x000D   x000D  myObject regex   undefined  x000D  myObject   JSON parse JSON stringify myObject    x000D   x000D  console log myObject   x000D   x000D   x000D

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Try the following method  Assign the Object property value to undefined  Then stringify the object and parse    x000D   x000D   var myObject     ircEvent    PRIVMSG    method    newURI    regex     http         x000D   x000D  myObject regex   undefined  x000D  myObject   JSON parse JSON stringify myObject    x000D   x000D  console log myObject   x000D   x000D   x000D

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The delete operator is used to remove properties from objects   const obj     foo   bar    delete obj foo obj hasOwnProperty  foo      false   Note that  for arrays  this is not the same as removing an element  To remove an element from an array  use Array splice or Array pop  For example   arr     0  1  2  3  4  arr splice 3 1      3 arr     0  1  2  4    Details  delete in JavaScript has a different function to that of the keyword in C and C    it does not directly free memory  Instead  its sole purpose is to remove properties from objects   For arrays  deleting a property corresponding to an index  creates a sparse array  ie  an array with a  hole  in it   Most browsers represent these missing array indices as  empty    var array    0  1  2  3  delete array 2      0  1  empty  3    Note that delete does not relocate array 3  into array 2    Different built-in functions in JavaScript handle sparse arrays differently    for   in will skip the empty index completely   A traditional for loop will return undefined for the value at the index  Any method using Symbol iterator will return undefined for the value at the index  forEach  map and reduce will simply skip the missing index    So  the delete operator should not be used for the common use-case of removing elements from an array  Arrays have a dedicated methods for removing elements and reallocating memory  Array splice   and Array pop   Array splice start   deleteCount   item1   item2             Array splice mutates the array  and returns any removed indices  deleteCount elements are removed from index start  and item1  item2    itemN are inserted into the array from index start  If deleteCount is omitted then elements from startIndex are removed to the end of the array   let a    0 1 2 3 4  a splice 2 2     returns the removed elements  2 3        and  a  is now  0 1 4    There is also a similarly named  but different  function on Array prototype  Array slice   Array slice  begin   end     Array slice is non-destructive  and returns a new array containing the indicated indices from start to end  If end is left unspecified  it defaults to the end of the array  If end is positive  it specifies the zero-based non-inclusive index to stop at  If end is negative it  it specifies the index to stop at by counting back from the end of the array  eg  -1 will omit the final index   If end  lt   start  the result is an empty array   let a    0 1 2 3 4  let slices         a slice 0 2       a slice 2 2       a slice 2 3       a slice 2 5          a            0 1 2 3 4       slices 0     0 1 - - -         slices 1     - - - - -      slices 2     - - 3 - -      slices 3     - - 2 4 5    Array pop  Array pop removes the last element from an array  and returns that element  This operation changes the length of the array

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Two ways to delete an object  using for in function deleteUser key      const newUsers         for  const uid in users           if  uid     key           newUsers uid    users uid       return newUsers      or delete users key

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Property Removal in JavaScript  There are many different options presented on this page  not because most of the options are wrong   or because the answers are duplicates   but because the appropriate technique depends on the situation you re in and the goals of the tasks you and or you team are trying to fulfill  To answer you question unequivocally  one needs to know    The version of ECMAScript you re targeting The range of object types you want to remove properties on and the type of property names you need to be able to omit  Strings only  Symbols  Weak references mapped from arbitrary objects  These have all been types of property pointers in JavaScript for years now  The programming ethos patterns you and your team use  Do you favor functional approaches and mutation is verboten on your team  or do you employ wild west mutative object-oriented techniques  Are you looking to achieve this in pure JavaScript or are you willing  amp  able to use a 3rd-party library    Once those four queries have been answered  there are essentially four categories of  property removal  in JavaScript to chose from in order to meet your goals  They are   Mutative object property deletion  unsafe  This category is for operating on object literals or object instances when you want to retain continue to use the original reference and aren t using stateless functional principles in your code  An example piece of syntax in this category    use strict  const iLikeMutatingStuffDontI     myNameIs   KIDDDDD     Symbol for  amICool     true   delete iLikeMutatingStuffDontI Symbol for  amICool       true Object defineProperty   myNameIs   KIDDDDD     amICool     value  true  configurable  false    delete iLikeMutatingStuffDontI  amICool      throws   This category is the oldest  most straightforward  amp  most widely supported category of property removal  It supports Symbol  amp  array indexes in addition to strings and works in every version of JavaScript except for the very first release  However  it s mutative which violates some programming principles and has performance implications  It also can result in uncaught exceptions when used on non-configurable properties in strict mode   Rest-based string property omission  This category is for operating on plain object or array instances in newer ECMAScript flavors when a non-mutative approach is desired and you don t need to account for Symbol keys   const foo     name   KIDDDDD     Symbol for  isCool     true   const   name     coolio     foo    coolio doesn t have  name  const   isCool     coolio2     foo    coolio2 has everything from  foo  because  isCool  doesn t account for Symbols      Mutative object property deletion  safe  This category is for operating on object literals or object instances when you want to retain continue to use the original reference while guarding against exceptions being thrown on unconfigurable properties    use strict  const iLikeMutatingStuffDontI     myNameIs   KIDDDDD     Symbol for  amICool     true   Reflect deleteProperty iLikeMutatingStuffDontI  Symbol for  amICool       true Object defineProperty   myNameIs   KIDDDDD     amICool     value  true  configurable  false    Reflect deleteProperty iLikeMutatingStuffDontI   amICool      false   In addition  while mutating objects in-place isn t stateless  you can use the functional nature of Reflect deleteProperty to do partial application and other functional techniques that aren t possible with delete statements   Syntax-based string property omission  This category is for operating on plain object or array instances in newer ECMAScript flavors when a non-mutative approach is desired and you don t need to account for Symbol keys   const foo     name   KIDDDDD     Symbol for  isCool     true   const   name     coolio     foo    coolio doesn t have  name  const   isCool     coolio2     foo    coolio2 has everything from  foo  because  isCool  doesn t account for Symbols      Library-based property omission  This category is generally allows for greater functional flexibility  including accounting for Symbols  amp  omitting more than one property in one statement   const o   require  lodash omit   const foo      Symbol for  a      abc   b   b   c   c    const bar   o foo   a        a  undefined  const baz   o foo    Symbol for  a     b        Symbol supported  more than one prop at a time   Symbol for  a   undefined

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You can use filter like below  x000D   x000D  var myObject          ircEvent    PRIVMSG        method    newURI        regex     http              way 1  let filter1        Object keys     myObject   filter d   gt      if d      regex        filter1 d    myObject d           console log filter1      way 2  let filter2   Object fromEntries Object entries     myObject   filter d   gt   d 0       regex      console log filter2  x000D   x000D   x000D

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If you don t want to modify the original object  Remove a property without mutating the object If mutability is a concern  you can create a completely new object by copying all the properties from the old  except the one you want to remove   x000D   x000D  let myObject        ircEvent    PRIVMSG      method    newURI      regex     http           let prop    regex   const updatedObject   Object keys myObject  reduce  object  key    gt      if  key     prop        object key    myObject key        return object         console log updatedObject   x000D   x000D   x000D

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If you want to delete a property deeply nested in the object then you can use the following recursive function with path to the property as the second argument   var deepObjectRemove   function obj  path to key       if path to key length     1           delete obj path to key 0            return true       else          if obj path to key 0                return deepObjectRemove obj path to key 0    path to key slice 1            else             return false             Example    var a         level1           level2               level3                    level4   yolo                                    deepObjectRemove a    level1    level2    level3     console log a      Prints  level1   level2

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The delete operator is used to remove properties from objects   const obj     foo   bar    delete obj foo obj hasOwnProperty  foo      false   Note that  for arrays  this is not the same as removing an element  To remove an element from an array  use Array splice or Array pop  For example   arr     0  1  2  3  4  arr splice 3 1      3 arr     0  1  2  4    Details  delete in JavaScript has a different function to that of the keyword in C and C    it does not directly free memory  Instead  its sole purpose is to remove properties from objects   For arrays  deleting a property corresponding to an index  creates a sparse array  ie  an array with a  hole  in it   Most browsers represent these missing array indices as  empty    var array    0  1  2  3  delete array 2      0  1  empty  3    Note that delete does not relocate array 3  into array 2    Different built-in functions in JavaScript handle sparse arrays differently    for   in will skip the empty index completely   A traditional for loop will return undefined for the value at the index  Any method using Symbol iterator will return undefined for the value at the index  forEach  map and reduce will simply skip the missing index    So  the delete operator should not be used for the common use-case of removing elements from an array  Arrays have a dedicated methods for removing elements and reallocating memory  Array splice   and Array pop   Array splice start   deleteCount   item1   item2             Array splice mutates the array  and returns any removed indices  deleteCount elements are removed from index start  and item1  item2    itemN are inserted into the array from index start  If deleteCount is omitted then elements from startIndex are removed to the end of the array   let a    0 1 2 3 4  a splice 2 2     returns the removed elements  2 3        and  a  is now  0 1 4    There is also a similarly named  but different  function on Array prototype  Array slice   Array slice  begin   end     Array slice is non-destructive  and returns a new array containing the indicated indices from start to end  If end is left unspecified  it defaults to the end of the array  If end is positive  it specifies the zero-based non-inclusive index to stop at  If end is negative it  it specifies the index to stop at by counting back from the end of the array  eg  -1 will omit the final index   If end  lt   start  the result is an empty array   let a    0 1 2 3 4  let slices         a slice 0 2       a slice 2 2       a slice 2 3       a slice 2 5          a            0 1 2 3 4       slices 0     0 1 - - -         slices 1     - - - - -      slices 2     - - 3 - -      slices 3     - - 2 4 5    Array pop  Array pop removes the last element from an array  and returns that element  This operation changes the length of the array

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Dan s assertion that  delete  is very slow and the benchmark he posted were doubted  So I carried out the test myself in Chrome 59  It does seem that  delete  is about 30 times slower   var iterationsTotal   10000000      10 million var o  var t1   Date now   t2  for  let i 0  i lt iterationsTotal  i         o    a 1 b 2 c 3 d 4 e 5      delete o a  delete o b  delete o c  delete o d  delete o e    console log   t2 Date now   -t1       6135 for  let i 0  i lt iterationsTotal  i         o    a 1 b 2 c 3 d 4 e 5      o a   o b   o c   o d   o e   undefined    console log  Date now  -t2       205   Note that I purposedly carried out more than one  delete  operations in one loop cycle to minimize the effect caused by the other operations

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x000D   x000D  var myObject     ircEvent    PRIVMSG    method    newURI    regex     http         x000D       x000D  delete myObject regex  x000D   x000D  console log   myObject regex      logs  undefined x000D   x000D   x000D    This works in Firefox and Internet nbsp Explorer  and I think it works in all others

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The obvious way to remove a property from an object is to use the delete keyword  this can be done like this  delete myObject  regex    or this  delete myObject regex  If you are cocerned with mutability  you can create a new object by copying all the properties from the old  except the one you would like to remove let myObject        ircEvent   quot PRIVMSG quot      method   quot newURI quot      regex   quot  http      quot      const propertyToRemove    regex  const newObject   Object keys myObject  reduce  object  key    gt       if  key     propertyToRemove           object key    car key       return object

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Using ramda dissoc you will get a new object without the attribute regex   const newObject   R dissoc  regex   myObject      newObject     myObject   You can also use other functions to achieve the same effect - omit  pick

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Here s an ES6 way to remove the entry easily    x000D   x000D  let myObject        ircEvent    PRIVMSG      method    newURI      regex     http           const removeItem    regex    const    removeItem   remove     rest     myObject   console log remove        http       console log rest      Object   ircEvent   PRIVMSG   method   newURI    x000D   x000D   x000D

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Old question  modern answer  Using object destructuring  an ECMAScript nbsp 6 feature  it s as simple as   const   a     rest       a  1  b  2  c  3      Or with the questions sample   const myObject     ircEvent    PRIVMSG    method    newURI    regex     http         const   regex     newObject     myObject  console log newObject     You can see it in action in the Babel try-out editor     Edit   To reassign to the same variable  use a let   let myObject     ircEvent    PRIVMSG    method    newURI    regex     http            regex     myObject     myObject   console log myObject

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Here s an ES6 way to remove the entry easily    x000D   x000D  let myObject        ircEvent    PRIVMSG      method    newURI      regex     http           const removeItem    regex    const    removeItem   remove     rest     myObject   console log remove        http       console log rest      Object   ircEvent   PRIVMSG   method   newURI    x000D   x000D   x000D

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There are a lot of good answers here but I just want to chime in that when using delete to remove a property in JavaScript  it is often wise to first check if that property exists to prevent errors   E g  var obj     property   value    property2   value     if  obj  amp  amp  obj hasOwnProperty  property2        delete obj property2    else       error handling     Due to the dynamic nature of JavaScript there are often cases where you simply don t know if the property exists or not  Checking if obj exists before the  amp  amp  also makes sure you don t throw an error due to calling the hasOwnProperty   function on an undefined object   Sorry if this didn t add to your specific use case but I believe this to be a good design to adapt when managing objects and their properties

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The term you have used in your question title Remove a property from a JavaScript object  can be interpreted in some different ways  The one is to remove it for whole the memory and the list of object keys or the other is just to remove it from your object  As it has been mentioned in some other answers  the delete keyword is the main part  Let s say you have your object like   myJSONObject     ircEvent    PRIVMSG    method    newURI    regex     http           If you do   console log Object keys myJSONObject      the result would be     ircEvent    method    regex     You can delete that specific key from your object keys like   delete myJSONObject  regex      Then your objects key using Object keys myJSONObject  would be     ircEvent    method     But the point is if you care about memory and you want to whole the object gets removed from the memory  it is recommended to set it to null before you delete the key   myJSONObject  regex     null  delete myJSONObject  regex      The other important point here is to be careful about your other references to the same object  For instance  if you create a variable like   var regex   myJSONObject  regex      Or add it as a new pointer to another object like   var myOtherObject       myOtherObject  regex     myJSONObject  regex      Then even if you remove it from your object myJSONObject  that specific object won t get deleted from the memory  since the regex variable and myOtherObject  regex   still have their values  Then how could we remove the object from the memory for sure   The answer would be to delete all the references you have in your code  pointed to that very object and also not use var statements to create new references to that object  This last point regarding var statements  is one of the most crucial issues that we are usually faced with  because using var statements would prevent the created object from getting removed   Which means in this case you won t be able to remove that object because you have created the regex variable via a var statement  and if you do   delete regex    False   The result would be false  which means that your delete statement haven t been executed as you expected  But if you had not created that variable before  and you only had myOtherObject  regex   as your last existing reference  you could have done this just by removing it like   myOtherObject  regex     null  delete myOtherObject  regex      In other words  a JavaScript object gets killed as soon as there is no reference left in your code pointed to that object     Update  Thanks to  AgentME      Setting a property to null before deleting it doesn t accomplish   anything  unless the object has been sealed by Object seal and the   delete fails  That s not usually the case unless you specifically   try     To get more info on Object seal  Object seal

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I have used lodash  unset  to make it happen for nested object also   only this need to write small logic to get path of property key which expected by omit method      Method which returns property path as array     x000D   x000D  var a     bool    must     range    price index final price    gt   450   lt   500       bool    should     term    color value keyword   Black           x000D   x000D  function getPathOfKey object key currentPath  t   x000D       var currentPath   currentPath        x000D   x000D      for var i in object   x000D    if i    key   x000D          t   currentPath  x000D          x000D        else if typeof object i      object    x000D          currentPath push i  x000D         return getPathOfKey object i   key currentPath  x000D          x000D        x000D   t push key   x000D      return t  x000D    x000D  document getElementById  output   innerHTML  JSON stringify getPathOfKey a  price index final price    x000D   lt div id  output  gt   x000D   x000D   lt  div gt  x000D   x000D   x000D     Then just using lodash unset method remove property from object      x000D   x000D  var unset   require  lodash unset    x000D  unset a getPathOfKey a  price index final price     x000D   x000D   x000D

[javascript] How do I remove a property from a JavaScript object?

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