Remove all elements contained in another array

Question

I am looking for an efficient way to remove all elements from a javascript array if they are present in another array      If I have this array  var myArray     a    b    c    d    e    f    g        and this one  var toRemove     b    c    g      I want to operate on myArray to leave it in this state    a    d    e    f    With jQuery  I m using grep   and inArray    which works well   myArray     grep myArray  function value        return   inArray value  toRemove   lt  0        Is there a pure javascript way to do this without looping and splicing

User · Answer

How about the simplest possible    x000D   x000D  var myArray     a    b    c    d    e    f    g    x000D  var toRemove     b    c    g    x000D   x000D  var myArray   myArray filter  item    gt   toRemove includes item    x000D  console log myArray  x000D   x000D   x000D

User · Answer

Proper way to remove all elements contained in another array is to make source array same object by remove only elements  Array prototype removeContained   function array      var i  results    i   this length    results         while  i--        if  array indexOf this i       -1          results push this splice i  1                return results      Or CoffeeScript equivalent  Array prototype removeContained    array  - gt    i    length    splice i  1 while i-- when array indexOf   i   isnt -1  Testing inside chrome dev tools   19 33 04 447 a 1 19 33 06 354 b 2 19 33 07 615 c 3 19 33 09 981 arr    a b c  19 33 16 460 arr1   arr 19 33 20 317 arr1     arr 19 33 20 331 true 19 33 43 592 arr removeContained  a c   19 33 52 433 arr     arr1 19 33 52 438 true  Using Angular framework is the best way to keep pointer to source object when you update collections without large amount of watchers and reloads

User · Answer

If you re using Typescript and want to match on a single property value  this should work based on Craciun Ciprian s answer above  You could also make this more generic by allowing non-object matching and   or multi-property value matching             param arr1 The initial array     param arr2 The array to remove     param propertyName the key of the object to match on     function differenceByPropVal lt T gt  arr1  T    arr2  T    propertyName  string   T       return arr1 filter       a  T   boolean   gt         arr2 find  b  T   boolean   gt  b propertyName      a propertyName

User · Answer

If you cannot use new ES5 stuff such filter I think you re stuck with two loops   for  var i  myArray length - 1  i gt  0  i--     for  var j 0  j lt toRemove length  j         if myArray i      toRemove j          myArray splice i  1

User · Answer

Now in one-liner flavor    x000D   x000D  console log   a    b    c    d    e    f    g   filter x   gt      b    c    g   indexOf x    x000D   x000D   x000D    Might not work on old browsers

User · Answer

var myArray        name   deepak   place   bangalore        name   chirag   place   bangalore        name   alok   place   berhampur        name   chandan   place   mumbai      var toRemove        name   deepak   place   bangalore       name   alok   place   berhampur         myArray   myArray filter ar   gt   toRemove find rm   gt   rm name     ar name  amp  amp  ar place     rm place

User · Answer

Lodash has an utility function for this as well  https   lodash com docs difference

User · Answer

I build the logic without using any built-in methods  please let me know any optimization or modifications  I tested in JS editor it is working fine   var myArray                  name   deepak   place   bangalore                 name   alok   place   berhampur                 name   chirag   place   bangalore                 name   chandan   place   mumbai                        var toRemove                   name   chirag   place   bangalore                 name   deepak   place   bangalore                   name   chandan   place   mumbai                     name   alok   place   berhampur                           var tempArr               for  var i 0   i  lt  myArray length  i                 for  var j 0  j lt toRemove length  j                     var toRemoveObj   toRemove j                   if myArray i   amp  amp   myArray i  name     toRemove j  name                         break                   else if myArray i   amp  amp   myArray i  name     toRemove j  name                            var fnd   isExists tempArr myArray i                            if  fnd                               var idx   getIdex toRemove myArray i                               if  idx     -1                                   tempArr push myArray i                                                                                                                         function isExists source item               var isFound   false              for  var i 0   i  lt  source length  i                     var obj   source i                   if item  amp  amp  obj  amp  amp  obj name     item name                       isFound   true                      break                                              return isFound                    function getIdex toRemove item               var idex   -1              for  var i 0   i  lt  toRemove length  i                     var rObj  toRemove i                   if rObj  amp  amp  item  amp  amp  rObj name     item name                       idex i                      break                                              return idex

User · Answer

If you are using an array of objects  Then the below code should do the magic  where an object property will be the criteria to remove duplicate items   In the below example  duplicates have been removed comparing name of each item   Try this example  http   jsfiddle net deepak7641 zLj133rh    x000D   x000D  var myArray     x000D     name   deepak   place   bangalore     x000D     name   chirag   place   bangalore     x000D     name   alok   place   berhampur     x000D     name   chandan   place   mumbai   x000D     x000D  var toRemove     x000D     name   deepak   place   bangalore    x000D     name   alok   place   berhampur   x000D     x000D   x000D  for  var i myArray length - 1  i gt  0  i--   x000D    for  var j 0  j lt toRemove length  j     x000D        if myArray i   amp  amp   myArray i  name     toRemove j  name    x000D        myArray splice i  1   x000D         x000D        x000D    x000D   x000D  alert JSON stringify myArray    x000D   x000D   x000D

User · Answer

The filter method should do the trick   const myArray     a    b    c    d    e    f    g    const toRemove     b    c    g        ES5 syntax const filteredArray   myArray filter function x       return toRemove indexOf x   lt  0        If your toRemove array is large  this sort of lookup pattern can be inefficient  It would be more performant to create a map so that lookups are O 1  rather than O n    const toRemoveMap   toRemove reduce    function memo  item        memo item    memo item     true      return memo               initialize an empty object     const filteredArray   myArray filter function  x      return toRemoveMap x           or  if you want to use ES6-style arrow syntax  const toRemoveMap   toRemove reduce  memo  item    gt          memo     item   true           const filteredArray   myArray filter x   gt  toRemoveMap x

User · Answer

You can use   differenceBy from lodash  const myArray        name   deepak   place   bangalore        name   chirag   place   bangalore        name   alok   place   berhampur        name   chandan   place   mumbai      const toRemove        name   deepak   place   bangalore       name   alok   place   berhampur      const sorted     differenceBy myArray  toRemove   name      Example code here  CodePen

User · Answer

ECMAScript 6 sets can permit faster computing of the elements of one array that aren t in the other   x000D   x000D  const myArray     a    b    c    d    e    f    g    const toRemove   new Set   b    c    g      const difference   myArray filter  x   gt   toRemove has x      console log difference        a    d    e    f   x000D   x000D   x000D   Since the lookup complexity for the V8 engine browsers use these days is O 1   the time complexity of the whole algorithm is O n

User · Answer

Use the Array filter   method   myArray   myArray filter  function  el       return toRemove indexOf  el    lt  0           Small improvement  as browser support for Array includes   has increased   myArray   myArray filter  function  el       return  toRemove includes  el             Next adaptation using arrow functions   myArray   myArray filter    el     gt   toRemove includes  el

User · Answer

I just implemented as   Array prototype exclude   function list           return this filter function el  return list indexOf el  lt 0        Use as   myArray exclude toRemove

[javascript] Remove all elements contained in another array

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