Javascript - removing undefined fields from an object

Question

Is there a clean way to remove undefined fields from an object   i e    gt  var obj     a  1  b  undefined  c  3    gt  removeUndefined obj    a  1  c  3     I came across two solutions     each query  function removeUndefined value  key      if    isUndefined value         delete query key             or     omit obj    filter   keys obj   function key    return   isUndefined obj key

User · Answer

This one is easy to remember  but might be slow  Use jQuery to copy non-null properties to an empty object  No deep copy unless you add true as first argument   myObj     extend     myObj

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Because it doesn t seem to have been mentioned  here s my preferred method  sans side effects or external dependencies    x000D   x000D  const obj     x000D    a  1  x000D    b  undefined x000D    x000D   x000D  const newObject   Object keys obj  reduce  acc  key    gt    x000D    const  acc   acc  x000D    if  obj key      undefined   acc key    obj key   x000D    return  acc  x000D         x000D   x000D  console log newObject  x000D     Object  a  1  x000D   x000D   x000D

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var obj     a  1  b  undefined  c  3    To remove undefined props in an object we use like this  JSON parse JSON stringify obj     Output   a  1  c  3

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Another Javascript Solution  for var i 0 keys   Object keys obj  len keys length i lt len i        if typeof obj keys i        undefined        delete obj keys i            No additional hasOwnProperty check is required as Object keys does not look up the prototype chain and returns only the properties of obj   DEMO

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I prefer to use something like Lodash   import   pickBy  identity   from  lodash   const cleanedObject   pickBy originalObject  identity    Note that the identity function is just x   gt  x and its result will be false for all falsy values  So this removes undefined      0  null       If you only want the undefined values removed you can do this   const cleanedObject   pickBy originalObject  v   gt  v     undefined    It gives you a new object  which is usually preferable over mutating the original object like some of the other answers suggest

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One could also use the JQuery filter for objects  var newobj     obj  filter function key        return   this  key     undefined       0     Demo here

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Mhh   I think  Damian asks for remove undefined field  property  from an JS object   Then  I would simply do      for  const i in myObj       if  typeof myObj i       undefined           delete myObj i      Short and efficient solution  in  vanilla  JS   Example     x000D   x000D  const myObj     x000D    a  1  x000D    b  undefined  x000D    c  null   x000D    d   hello world  x000D     x000D   x000D  for  const i in myObj    x000D    if  typeof myObj i       undefined      x000D      delete myObj i    x000D   x000D  console log myObj   x000D   x000D   x000D

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A one-liner using ES6 arrow function and ternary operator  Object keys obj  forEach key   gt  obj key      undefined   delete obj key          Or use short-circuit evaluation instead of ternary    Matt Langlois  thanks for the info   Object keys obj  forEach key   gt  obj key      undefined  amp  amp  delete obj key    Same example using if statement  Object keys obj  forEach key   gt      if  obj key      undefined        delete obj key            If you want to remove the items from nested objects as well  you can use a recursive function  const removeEmpty    obj    gt      let newObj         Object keys obj  forEach  key    gt        if  obj key      Object obj key    newObj key    removeEmpty obj key        else if  obj key      undefined  newObj key    obj key           return newObj

User · Answer

Here s a plain javascript  no library required  solution   function removeUndefinedProps obj        for  var prop in obj            if  obj hasOwnProperty prop   amp  amp  obj prop      undefined                delete obj prop                       Working demo  http   jsfiddle net jfriend00 djj5g5fu

User · Answer

This solution also avoids hasOwnProperty   as Object keys returns an array of a given object s own enumerable properties   Object keys obj  forEach function  key     if typeof obj key       undefined        delete obj key             and you can add this as null or    for stricter cleaning

[javascript] Javascript - removing undefined fields from an object

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