JavaScript equivalent of PHP s in array

Question

Is there a way in JavaScript to compare values from one array and see if it is in another array    Similar to PHP s in array function

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An equivalent of in array with underscore is   indexOf     Examples     indexOf  3  5  8   8        returns 2  the index of 8   indexOf  3  5  8   10        returns -1  not found

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I found a great jQuery solution here on SO   var success     grep array a  function v i        return   inArray v  array b      -1     length     array a length    I wish someone would post an example of how to do this in underscore

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There is now Array prototype includes      The includes   method determines whether an array includes a certain   element  returning true or false as appropriate    var a    1  2  3   a includes 2      true  a includes 4      false      Syntax   arr includes searchElement  arr includes searchElement  fromIndex

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There is an equivalent function   includes     Look here   https   developer mozilla org en-US docs Web JavaScript Reference Global Objects Array includes

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With Dojo Toolkit  you would use dojo indexOf    See dojo indexOf for the documentation  and Arrays Made Easy by Bryan Forbes for some examples

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If you are going to use it in a class  and if you prefer it to be functional  and work in all browsers    inArray  function needle  haystack        var result   false       for  var i in haystack            if  haystack i      needle                result   true              break                       return result      Hope it helps someone  -

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You can simply use the  includes  function as explained in this lesson on w3schools  it looks like   x000D   x000D  let myArray     Kevin    Bob    Stuart    x000D  if  myArray includes  Kevin    x000D  console log  Kevin is here    x000D   x000D   x000D

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haystack find value   gt  value    needle    where haystack is an array and needle is an element in array  If element not found will be returned undefined else the same element

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function in array needle  haystack        return haystack indexOf needle      -1

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If the indexes are not in sequence  or if the indexes are not consecutive  the code in the other solutions listed here will break   A solution that would work somewhat better might be   function in array needle  haystack        for var i in haystack            if haystack i     needle  return true            return false      And  as a bonus  here s the equivalent to PHP s array search  for finding the key of the element in the array   function array search needle  haystack        for var i in haystack            if haystack i     needle  return i            return false

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PHP way  if  in array  a     a    b    c             do something if true    My solution in JS  if    a    b    c   includes  a            do something if true

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var a    1 2 3 4 5 6 7 8 9    var isSixInArray   a filter function item  return item  6   length   true   false   var isSixInArray   a indexOf 6  gt  0

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function in array what  where        var a false      for  var i 0  i lt where length  i              if what    where i                 a true              break                      return a

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If you need all the PHP available parameters  use this   function in array needle  haystack  argStrict        var key       strict     argStrict      if  strict            for  key in haystack                if  haystack key      needle                    return true                                    else           for  key in haystack                if  haystack key     needle                    return true                                    return false

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No  it doesn t have one  For this reason most popular libraries come with one in their utility packages  Check out jQuery s inArray and Prototype s Array indexOf for examples    jQuery s implementation of it is as simple as you might expect   function inArray needle  haystack        var length   haystack length      for var i   0  i  lt  length  i              if haystack i     needle  return true            return false      If you are dealing with a sane amount of array elements the above will do the trick nicely   EDIT  Whoops  I didn t even notice you wanted to see if an array was inside another  According to the PHP documentation this is the expected behavior of PHP s in array    a   array array  p    h    array  p    r     o     if  in array array  p    h     a         echo   ph  was found n      if  in array array  f    i     a         echo   fi  was found n      if  in array  o    a         echo   o  was found n         Output       ph  was found      o  was found   The code posted by Chris and Alex does not follow this behavior  Alex s is the official version of Prototype s indexOf  and Chris s is more like PHP s array intersect  This does what you want   function arrayCompare a1  a2        if  a1 length    a2 length  return false      var length   a2 length      for  var i   0  i  lt  length  i              if  a1 i      a2 i   return false            return true     function inArray needle  haystack        var length   haystack length      for var i   0  i  lt  length  i              if typeof haystack i      object                 if arrayCompare haystack i   needle   return true            else               if haystack i     needle  return true                      return false      And this my test of the above on it   var a      p   h     p   r    o    if inArray   p   h    a         alert  ph was found      if inArray   f   i    a         alert  fi was found      if inArray  o   a         alert  o was found           Results       alerts  ph  was found      alerts  o  was found   Note that I intentionally did not extend the Array prototype as it is generally a bad idea to do so

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There is a project called Locutus  it implements PHP functions in Javascript and in array   is included  you can use it exactly as you use in PHP   Examples of use   in array  van   myArray    in array 1  otherArray  true      Forcing strict type

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Add this code to you project and use the object-style inArray methods  if   Array prototype inArray        Array prototype inArray   function element            return this indexOf element   gt  -1              How it work var array     one    two    three      Return true array inArray  one

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Array indexOf was introduced in JavaScript 1 6  but it is not supported in older browsers  Thankfully the chaps over at Mozilla have done all the hard work for you  and provided you with this for compatibility   if   Array prototype indexOf      Array prototype indexOf   function elt     from            var len   this length  gt  gt  gt  0       var from   Number arguments 1      0      from    from  lt  0             Math ceil from             Math floor from       if  from  lt  0        from    len       for    from  lt  len  from                if  from in this  amp  amp            this from      elt          return from            return -1           There are even some handy usage snippets for your scripting pleasure

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jQuery solution is available  check the ducumentation here  http   api jquery com jquery inarray     inArray  10    8  9  10  11

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If you only want to check if a single value is in an array  then Paolo s code will do the job  If you want to check which values are common to both arrays  then you ll want something like this  using Paolo s inArray function    function arrayIntersect a  b        var intersection            for var i   0  i  lt  a length  i              if inArray b  a i                intersection push a i               return intersection      This wil return an array of values that are in both a and b   Mathematically  this is an intersection of the two arrays    EDIT  See Paolo s Edited Code for the solution to your problem

[php] JavaScript equivalent of PHP's in_array()

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