How to filter an array from all elements of another array

Question

I d like to understand the best way to filter an array from all elements of another one  I tried with the filter function  but it doesn t come to me how to give it the values i want to remove   Something Like   var array    1 2 3 4   var anotherOne    2 4   var filteredArray   array filter myCallback      filteredArray should now be  1 3    function myCallBack        return element   filteredArray         which clearly can t work since we don t have the reference  lt   lt       in case the filter function is not usefull  how would you implement this   Edit  i checked the possible duplicate question  and it could be useful for those who understand javascript easily  The answer checked as good makes things easy

User · Answer

The best description to filter function is https   developer mozilla org pl docs Web JavaScript Referencje Obiekty Array filter  You should simply condition function   function conditionFun element  index  array       return element  gt   10    filtered    12  5  8  130  44  filter conditionFun     And you can t access the variable value before it is assigned

User · Answer

var array    1 2 3 4   var anotherOne    2 4   var filteredArray   array filter myCallBack    function myCallBack el     return anotherOne indexOf el   lt  0      In the callback  you check if each value of array is in anotherOne  https   jsfiddle net 0tsyc1sx   If you are using lodash js  use   difference   filteredArray     difference array  anotherOne     Demo  If you have an array of objects    var array     id  1  name   test1    id  2  name   test2    id  3  name   test3    id  4  name   test4      var anotherOne     id  2  name   test2     id  4  name   test4      var filteredArray    array filter function array el      return anotherOne filter function anotherOne el         return anotherOne el id    array el id        length    0       Demo array of objects  Demo diff array of objects with lodash

User · Answer

with object filter result   id 1   id 2   id 3   id 4   filter v  gt     id 2   id 4   some e  gt e id     v id

User · Answer

You can write a generic filterByIndex   function and make use of type inference in TS to save the hassle with the callback function   let s say you have your array  1 2 3 4  that you want to filter   with the indices specified in the  2 4  array   var filtered    1 2 3 4   filter byIndex element   gt  element   2 4      the byIndex function expects the element function and an array and looks like this   byIndex    getter   e number    gt  number  arr  number      gt   x  number    gt        var i   getter x       return arr indexOf i        result is then   filtered    1 3

User · Answer

x000D   x000D  var arr1   1 2 3 4   x000D  var arr2  2 4  x000D   x000D  function fil value   x000D  return value   arr2 0   amp  amp   value    arr2 1  x000D    x000D   x000D  document getElementById  p   innerHTML  arr1 filter fil  x000D   lt  DOCTYPE html gt   x000D   lt html gt   x000D   lt head gt   x000D   lt  head gt  x000D   lt body gt  x000D   lt p id  p  gt  lt  p gt  x000D   x000D   x000D

User · Answer

If you need to compare an array of objects  this works in all cases  let arr      id  1  title   quot title1 quot      id  2  title   quot title2 quot     let brr      id  2  title   quot title2 quot      id  3  title   quot title3 quot      const res   arr filter f   gt  brr some item   gt  item id     f id    console log res

User · Answer

The solution of Jack Giffin is great but doesn t work for arrays with numbers bigger than 2 32  Below is a refactored  fast version to filter an array based on Jack s solution but it works for 64-bit arrays   const Math clz32   Math clz32      log  LN2    gt  x   gt  31 - log x  gt  gt  gt  0    LN2   0  Math log  Math LN2    const filterArrayByAnotherArray    searchArray  filterArray    gt         searchArray sort  a b    gt  a  gt  b       filterArray sort  a b    gt  a  gt  b        let searchArrayLen   searchArray length  filterArrayLen   filterArray length      let progressiveLinearComplexity     searchArrayLen lt  lt 1    filterArrayLen  gt  gt  gt 0     let binarySearchComplexity    searchArrayLen    32-Math clz32 filterArrayLen-1    gt  gt  gt 0       let i   0       if  progressiveLinearComplexity  lt  binarySearchComplexity          return searchArray filter currentValue   gt            while  filterArray i   lt  currentValue  i i 1 0          return filterArray i      currentValue                      else return searchArray filter e   gt  binarySearch filterArray  e      null      const binarySearch    sortedArray  elToFind    gt      let lowIndex   0    let highIndex   sortedArray length - 1    while  lowIndex  lt   highIndex        let midIndex   Math floor  lowIndex   highIndex    2       if  sortedArray midIndex     elToFind  return midIndex       else if  sortedArray midIndex   lt  elToFind  lowIndex   midIndex   1      else highIndex   midIndex - 1      return null

User · Answer

The OA can also be implemented in ES6 as follows  ES6    const filtered    1  2  3  4  filter e   gt        return this indexOf e   lt  0       2  4

User · Answer

The following examples use new Set   to create a filtered array that has only unique elements   Array with primitive data types  string  number  boolean  null  undefined  symbol   const a    1  2  3  4   const b    3  4  5   const c   Array from new Set a concat b       Array with objects as items   const a     id 1    id  2    id  3    id  4    const b     id  3    id  4    id  5    const stringifyObject   o   gt  JSON stringify o   const parseString   s   gt  JSON parse s   const c   Array from new Set a concat b  map stringifyObject    parseString

User · Answer

I would do as follows   x000D   x000D  var arr1    1 2 3 4       arr2    2 4       res   arr1 filter item   gt   arr2 includes item    console log res   x000D   x000D   x000D

User · Answer

x000D   x000D  function arr arr1 arr2   x000D     x000D    function filt value   x000D      return arr2 indexOf value      -1  x000D        x000D     x000D    return arr1 filter filt  x000D      x000D   x000D  document getElementById  p   innerHTML   arr  1 2 3 4   2 4   x000D   lt p id  p  gt  lt  p gt  x000D   x000D   x000D

User · Answer

You can use the filter and then for the filter function use a reduction of the filtering array which checks and returns true when it finds a match then invert on return       The filter function is called once per element in the array   You are not doing a comparison of any of the elements in the function in your post    x000D   x000D  var a1    1  2  3  4   x000D    a2    2  3   x000D   x000D  var filtered   a1 filter function x    x000D    return  a2 reduce function y  z    x000D      return x    y    x    z    y    true  x000D       x000D      x000D   x000D  document write filtered   x000D   x000D   x000D

User · Answer

You can use the this parameter of the filter   function to avoid to store your filter array in a global variable    x000D   x000D  var filtered    1  2  3  4  filter  x000D      function e    x000D        return this indexOf e   lt  0  x000D         x000D       2  4  x000D     x000D  console log filtered   x000D   x000D   x000D

User · Answer

A more flexible filtering array from another array which contain object properties   x000D   x000D  function filterFn array  diffArray  prop  propDiff    x000D      diffArray    propDiff   diffArray   diffArray map d   gt  d propDiff   x000D      this fn   f   gt  diffArray indexOf f      -1 x000D      if  prop    x000D           return array map r   gt  r prop   filter this fn  x000D        else   x000D           return array filter this fn  x000D        x000D    x000D   x000D    You can use it like this  x000D   x000D  var arr       x000D   x000D  for  var i   0  i  lt  10  i      x000D      var obj      x000D      obj index   i x000D      obj value   Math pow 2  i  x000D      arr push obj  x000D    x000D   x000D  var arr2    1  2  3  4  5  x000D   x000D  var sec     t 2    t 99    t 256    t 4096   x000D   x000D  var log   console log bind console  x000D   x000D  var filtered   filterFn arr  sec   value    t   x000D   x000D  var filtered2   filterFn arr2  sec  null   t   x000D   x000D  log filtered  filtered2  x000D   x000D   x000D

User · Answer

x000D   x000D             Here s an example that uses  some  ES6 Javascript semantics to filter an object array by another object array     x000D   x000D             x   full dataset x000D             y   filter dataset x000D          let x     x000D                val   1   text    a    x000D                val   2   text    b    x000D                val   3   text    c    x000D                val   4   text    d    x000D                val   5   text    e   x000D                 x000D              y     x000D                val   1   text    a    x000D                val   4   text    d                  x000D                 x000D   x000D             Use map to get a simple array of  val  values  Ex   1 4  x000D          let yFilter   y map itemY   gt    return itemY val      x000D   x000D             Use filter and  not  includes to filter the full dataset by the filter dataset s val  x000D          let filteredX   x filter itemX   gt   yFilter includes itemX val    x000D   x000D             Print the result  x000D          console log filteredX   x000D   x000D   x000D

User · Answer

You can setup the filter function to iterate over the  filter array    var arr    1  2  3  4  5  6  7   var filter    4  5  6    var filtered   arr filter    function val        for  var i   0  i  lt  filter length  i            if  val    filter i             return false                    return true

User · Answer

The code below is the simplest way to filter an array with respect to another array  Both arrays can have objects inside them instead of values   x000D   x000D  let array1    1  3  47  1  6  7   let array2    3  6   let filteredArray1   array1 filter el   gt  array2 includes el    console log filteredArray1    x000D   x000D   x000D   Output   3  6

User · Answer

There are many answers for your question  but I don t see anyone using lambda expresion   var array    1 2 3 4   var anotherOne    2 4   var filteredArray   array filter x   gt  anotherOne indexOf x   lt  0

User · Answer

All the above solutions  quot work quot   but are less than optimal for performance and are all approach the problem in the same way which is linearly searching all entries at each point using Array prototype indexOf or Array prototype includes  A far faster solution  far faster even than a binary search for most cases  would be to sort the arrays and skip ahead as you go along as seen below  However  one downside is that this requires all entries in the array to be numbers or strings  Also however  binary search may in some rare cases be faster than the progressive linear search  These cases arise from the fact that my progressive linear search has a complexity of O 2n1 n2   only O n1 n2  in the faster C C   version   where n1 is the searched array and n2 is the filter array   whereas the binary search has a complexity of O n1ceil log2n2    ceil   round up -- to the ceiling   and  lastly  the indexOf search has a highly variable complexity between O n1  and O n1n2   averaging out to O n1ceil n2  2    Thus  indexOf will only be the fastest  on average  in the cases of  n1 n2  equaling  1 2    1 3   or  x 1 x N   However  this is still not a perfect representation of modern hardware  IndexOf is natively optimized to the fullest extent imaginable in most modern browsers  making it very subject to the laws of branch prediction  Thus  if we make the same assumption on indexOf as we do with progressive linear and binary search -- that the array is presorted -- then  according to the stats listed in the link  we can expect roughly a 6x speed up for IndexOf  shifting its complexity to between O n1  6  and O n1n2   averaging out to O n1ceil n27  12    Finally  take note that the below solution will never work with objects because objects in JavaScript cannot be compared by pointers in JavaScript  function sortAnyArray a b    return a gt b   1    a   b   0   -1     function sortIntArray a b    return  a 0  -  b 0   0    function fastFilter array  handle        var out     value 0      for  var i 0   len array length 0  i  lt  len  i i 1 0          if  handle value   array i                 out push  value        return out     const Math clz32   Math clz32     function log  LN2     return function x        return 31 - log x  gt  gt  gt  0    LN2   0     the  quot   0 quot  acts like math floor         Math log  Math LN2       USAGE    filterArrayByAnotherArray         1 3 5          2 3 4      yields  1  5   and it can work with strings too    function filterArrayByAnotherArray searchArray  filterArray        if              NOTE  This does not check the whole array  But  if you know                   that there are only strings or numbers  not a mix of                   both  in the array  then this is a safe assumption             Always use      with  typeof  because browsers can optimize             the      into        ONLY IN THIS CIRCUMSTANCE          typeof searchArray 0      quot number quot   amp  amp          typeof filterArray 0      quot number quot   amp  amp           searchArray 0  0      searchArray 0   amp  amp           filterArray 0  0      filterArray 0         filterArray            if all entries in both arrays are integers         searchArray sort sortIntArray           filterArray sort sortIntArray         else           searchArray sort sortAnyArray           filterArray sort sortAnyArray             var searchArrayLen   searchArray length  filterArrayLen   filterArray length      var progressiveLinearComplexity     searchArrayLen lt  lt 1    filterArrayLen  gt  gt  gt 0     var binarySearchComplexity   searchArrayLen    32-Math clz32 filterArrayLen-1    gt  gt  gt 0         After computing the complexity  we can predict which algorithm will be the fastest     var i   0      if  progressiveLinearComplexity  lt  binarySearchComplexity               Progressive Linear Search         return fastFilter searchArray  function currentValue               while  filterArray i   lt  currentValue  i i 1 0                  undefined   NaN  which is always false for  lt   avoiding an infinite loop             return filterArray i      currentValue                    else              Binary Search         return fastFilter              searchArray              fastestBinarySearch filterArray                         see https   stackoverflow com a 44981570 5601591 for implementation     details about this binary search algorithm  function fastestBinarySearch array     var initLen    array length 0  - 1  0       const compGoto   Math clz32 initLen   amp  31    return function sValue        var len   initLen  0      switch  compGoto          case 0          if  len  amp  0x80000000              const nCB   len  amp  0x80000000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 1          if  len  amp  0x40000000              const nCB   len  amp  0xc0000000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 2          if  len  amp  0x20000000              const nCB   len  amp  0xe0000000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 3          if  len  amp  0x10000000              const nCB   len  amp  0xf0000000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 4          if  len  amp  0x8000000              const nCB   len  amp  0xf8000000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 5          if  len  amp  0x4000000              const nCB   len  amp  0xfc000000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 6          if  len  amp  0x2000000              const nCB   len  amp  0xfe000000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 7          if  len  amp  0x1000000              const nCB   len  amp  0xff000000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 8          if  len  amp  0x800000              const nCB   len  amp  0xff800000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 9          if  len  amp  0x400000              const nCB   len  amp  0xffc00000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 10          if  len  amp  0x200000              const nCB   len  amp  0xffe00000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 11          if  len  amp  0x100000              const nCB   len  amp  0xfff00000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 12          if  len  amp  0x80000              const nCB   len  amp  0xfff80000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 13          if  len  amp  0x40000              const nCB   len  amp  0xfffc0000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 14          if  len  amp  0x20000              const nCB   len  amp  0xfffe0000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 15          if  len  amp  0x10000              const nCB   len  amp  0xffff0000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 16          if  len  amp  0x8000              const nCB   len  amp  0xffff8000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 17          if  len  amp  0x4000              const nCB   len  amp  0xffffc000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 18          if  len  amp  0x2000              const nCB   len  amp  0xffffe000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 19          if  len  amp  0x1000              const nCB   len  amp  0xfffff000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 20          if  len  amp  0x800              const nCB   len  amp  0xfffff800            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 21          if  len  amp  0x400              const nCB   len  amp  0xfffffc00            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 22          if  len  amp  0x200              const nCB   len  amp  0xfffffe00            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 23          if  len  amp  0x100              const nCB   len  amp  0xffffff00            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 24          if  len  amp  0x80              const nCB   len  amp  0xffffff80            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 25          if  len  amp  0x40              const nCB   len  amp  0xffffffc0            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 26          if  len  amp  0x20              const nCB   len  amp  0xffffffe0            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 27          if  len  amp  0x10              const nCB   len  amp  0xfffffff0            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 28          if  len  amp  0x8              const nCB   len  amp  0xfffffff8            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 29          if  len  amp  0x4              const nCB   len  amp  0xfffffffc            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 30          if  len  amp  0x2              const nCB   len  amp  0xfffffffe            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 31          if  len  amp  0x1              const nCB   len  amp  0xffffffff            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                          MODIFICATION  Instead of returning the index  this binary search                       instead returns whether something was found or not      if  array len 0      sValue           return true     preserve the value at this index       else          return false     eliminate the value at this index               Please see my other post here for more details on the binary search algorithm used If you are squeamish about file size  which I respect   then you can sacrifice a little performance in order to greatly reduce the file size and increase maintainability  function sortAnyArray a b    return a gt b   1    a   b   0   -1     function sortIntArray a b    return  a 0  -  b 0   0    function fastFilter array  handle        var out     value 0      for  var i 0   len array length 0  i  lt  len  i i 1 0          if  handle value   array i                 out push  value        return out        USAGE    filterArrayByAnotherArray         1 3 5          2 3 4      yields  1  5   and it can work with strings too    function filterArrayByAnotherArray searchArray  filterArray        if              NOTE  This does not check the whole array  But  if you know                   that there are only strings or numbers  not a mix of                   both  in the array  then this is a safe assumption          typeof searchArray 0      quot number quot   amp  amp          typeof filterArray 0      quot number quot   amp  amp           searchArray 0  0      searchArray 0   amp  amp           filterArray 0  0      filterArray 0                     if all entries in both arrays are integers         searchArray sort sortIntArray           filterArray sort sortIntArray         else           searchArray sort sortAnyArray           filterArray sort sortAnyArray                Progressive Linear Search     var i   0      return fastFilter searchArray  function currentValue           while  filterArray i   lt  currentValue  i i 1 0              undefined   NaN  which is always false for  lt   avoiding an infinite loop         return filterArray i      currentValue             To prove the difference in speed  let us examine some JSPerfs  For filtering an array of 16 elements  binary search is roughly 17  faster than indexOf while filterArrayByAnotherArray is roughly 93  faster than indexOf  For filtering an array of 256 elements  binary search is roughly 291  faster than indexOf while filterArrayByAnotherArray is roughly 353  faster than indexOf  For filtering an array of 4096 elements  binary search is roughly 2655  faster than indexOf while filterArrayByAnotherArray is roughly 4627  faster than indexOf  Reverse-filtering  like an AND gate  The previous section provided code to take array A and array B  and remove all elements from A that exist in B  filterArrayByAnotherArray       1 3 5        2 3 4        yields  1  5   This next section will provide code for reverse-filtering  where we remove all elements from A that DO NOT exist in B  This process is functionally equivalent to only retaining the elements common to both A and B  like an AND gate  reverseFilterArrayByAnotherArray       1 3 5        2 3 4        yields  3   Here is the code for reverse filtering  function sortAnyArray a b    return a gt b   1    a   b   0   -1     function sortIntArray a b    return  a 0  -  b 0   0    function fastFilter array  handle        var out     value 0      for  var i 0   len array length 0  i  lt  len  i i 1 0          if  handle value   array i                 out push  value        return out     const Math clz32   Math clz32     function log  LN2     return function x        return 31 - log x  gt  gt  gt  0    LN2   0     the  quot   0 quot  acts like math floor         Math log  Math LN2       USAGE    reverseFilterArrayByAnotherArray         1 3 5          2 3 4      yields  3   and it can work with strings too    function reverseFilterArrayByAnotherArray searchArray  filterArray        if              NOTE  This does not check the whole array  But  if you know                   that there are only strings or numbers  not a mix of                   both  in the array  then this is a safe assumption             Always use      with  typeof  because browsers can optimize             the      into        ONLY IN THIS CIRCUMSTANCE          typeof searchArray 0      quot number quot   amp  amp          typeof filterArray 0      quot number quot   amp  amp           searchArray 0  0      searchArray 0   amp  amp           filterArray 0  0      filterArray 0                     if all entries in both arrays are integers         searchArray sort sortIntArray           filterArray sort sortIntArray         else           searchArray sort sortAnyArray           filterArray sort sortAnyArray             var searchArrayLen   searchArray length  filterArrayLen   filterArray length      var progressiveLinearComplexity     searchArrayLen lt  lt 1    filterArrayLen  gt  gt  gt 0     var binarySearchComplexity   searchArrayLen    32-Math clz32 filterArrayLen-1    gt  gt  gt 0         After computing the complexity  we can predict which algorithm will be the fastest     var i   0      if  progressiveLinearComplexity  lt  binarySearchComplexity               Progressive Linear Search         return fastFilter searchArray  function currentValue               while  filterArray i   lt  currentValue  i i 1 0                  undefined   NaN  which is always false for  lt   avoiding an infinite loop                For reverse filterning  I changed     to                 return filterArray i      currentValue                    else              Binary Search         return fastFilter              searchArray              inverseFastestBinarySearch filterArray                         see https   stackoverflow com a 44981570 5601591 for implementation     details about this binary search algorithim  function inverseFastestBinarySearch array     var initLen    array length 0  - 1  0       const compGoto   Math clz32 initLen   amp  31    return function sValue        var len   initLen  0      switch  compGoto          case 0          if  len  amp  0x80000000              const nCB   len  amp  0x80000000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 1          if  len  amp  0x40000000              const nCB   len  amp  0xc0000000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 2          if  len  amp  0x20000000              const nCB   len  amp  0xe0000000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 3          if  len  amp  0x10000000              const nCB   len  amp  0xf0000000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 4          if  len  amp  0x8000000              const nCB   len  amp  0xf8000000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 5          if  len  amp  0x4000000              const nCB   len  amp  0xfc000000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 6          if  len  amp  0x2000000              const nCB   len  amp  0xfe000000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 7          if  len  amp  0x1000000              const nCB   len  amp  0xff000000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 8          if  len  amp  0x800000              const nCB   len  amp  0xff800000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 9          if  len  amp  0x400000              const nCB   len  amp  0xffc00000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 10          if  len  amp  0x200000              const nCB   len  amp  0xffe00000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 11          if  len  amp  0x100000              const nCB   len  amp  0xfff00000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 12          if  len  amp  0x80000              const nCB   len  amp  0xfff80000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 13          if  len  amp  0x40000              const nCB   len  amp  0xfffc0000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 14          if  len  amp  0x20000              const nCB   len  amp  0xfffe0000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 15          if  len  amp  0x10000              const nCB   len  amp  0xffff0000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 16          if  len  amp  0x8000              const nCB   len  amp  0xffff8000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 17          if  len  amp  0x4000              const nCB   len  amp  0xffffc000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 18          if  len  amp  0x2000              const nCB   len  amp  0xffffe000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 19          if  len  amp  0x1000              const nCB   len  amp  0xfffff000            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 20          if  len  amp  0x800              const nCB   len  amp  0xfffff800            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 21          if  len  amp  0x400              const nCB   len  amp  0xfffffc00            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 22          if  len  amp  0x200              const nCB   len  amp  0xfffffe00            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 23          if  len  amp  0x100              const nCB   len  amp  0xffffff00            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 24          if  len  amp  0x80              const nCB   len  amp  0xffffff80            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 25          if  len  amp  0x40              const nCB   len  amp  0xffffffc0            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 26          if  len  amp  0x20              const nCB   len  amp  0xffffffe0            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 27          if  len  amp  0x10              const nCB   len  amp  0xfffffff0            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 28          if  len  amp  0x8              const nCB   len  amp  0xfffffff8            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 29          if  len  amp  0x4              const nCB   len  amp  0xfffffffc            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 30          if  len  amp  0x2              const nCB   len  amp  0xfffffffe            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                   case 31          if  len  amp  0x1              const nCB   len  amp  0xffffffff            len     len    nCB-1    amp    array nCB   lt   sValue  0  - 1  gt  gt  gt 0                          MODIFICATION  Instead of returning the index  this binary search                       instead returns whether something was found or not         For reverse filterning  I swapped true with false and vice-versa     if  array len 0      sValue           return false     preserve the value at this index       else          return true     eliminate the value at this index               For the slower smaller version of the reverse filtering code  see below  function sortAnyArray a b    return a gt b   1    a   b   0   -1     function sortIntArray a b    return  a 0  -  b 0   0    function fastFilter array  handle        var out     value 0      for  var i 0   len array length 0  i  lt  len  i i 1 0          if  handle value   array i                 out push  value        return out        USAGE    reverseFilterArrayByAnotherArray         1 3 5          2 3 4      yields  3   and it can work with strings too    function reverseFilterArrayByAnotherArray searchArray  filterArray        if              NOTE  This does not check the whole array  But  if you know                   that there are only strings or numbers  not a mix of                   both  in the array  then this is a safe assumption          typeof searchArray 0      quot number quot   amp  amp          typeof filterArray 0      quot number quot   amp  amp           searchArray 0  0      searchArray 0   amp  amp           filterArray 0  0      filterArray 0                     if all entries in both arrays are integers         searchArray sort sortIntArray           filterArray sort sortIntArray         else           searchArray sort sortAnyArray           filterArray sort sortAnyArray                Progressive Linear Search     var i   0      return fastFilter searchArray  function currentValue           while  filterArray i   lt  currentValue  i i 1 0              undefined   NaN  which is always false for  lt   avoiding an infinite loop            For reverse filter  I changed     to             return filterArray i      currentValue

User · Answer

Below is an example   x000D   x000D  let firstArray  1 2 3 4 5   x000D  let secondArray  2 3     x000D  let filteredArray   firstArray filter  a    gt  secondArray indexOf a  lt 0   x000D  console log filteredArray     above line gives  1 4 5  x000D   x000D   x000D

[javascript] How to filter an array from all elements of another array

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