How to fix Array indexOf in JavaScript for Internet Explorer browsers

Question

If you have worked with JavaScript at any length you are aware that Internet nbsp Explorer does not implement the ECMAScript function for Array prototype indexOf    including Internet nbsp Explorer nbsp 8   It is not a huge problem  because you can extend the functionality on your page with the following code   Array prototype indexOf   function obj  start         for  var i    start    0   j   this length  i  lt  j  i               if  this i      obj    return i                return -1      When should I implement this   Should I wrap it on all my pages with the following check  which checks if the prototype function exists and if not  go ahead and extend the Array prototype   if   Array prototype indexOf            Implement function here      Or do browser check and if it is Internet nbsp Explorer then just implement it     Pseudo-code  if  browser    IE Style Browser             Implement function here

User · Answer

Alternatively  you could use the jQuery 1 2 inArray function  which should work across browsers   jQuery inArray  value  array    fromIndex

User · Answer

You should check if it s not defined using if   Array prototype indexOf    Also  your implementation of indexOf is not correct  You must use     instead of    in your if  this i     obj  statement  otherwise  4  5   indexOf 5  would be 1 according to your implementation  which is incorrect   I recommend you use the implementation on MDC

User · Answer

Do it like this     if   Array prototype indexOf         As recommended compatibility by MDC   In general  browser detection code is a big no-no

User · Answer

There is Mozilla official solution  https   developer mozilla org en-US docs Web JavaScript Reference Global Objects Array indexOf   function            Array          Production steps of ECMA-262  Edition 5  15 4 4 14        Reference  http   es5 github io  x15 4 4 14     if   Array prototype indexOf            Array prototype indexOf   function searchElement  fromIndex                var k                 1  Let O be the result of calling ToObject passing                   the this value as the argument              if  null     this    undefined     this                    throw new TypeError   this  is null or not defined                              var O   Object this                  2  Let lenValue be the result of calling the Get                   internal method of O with the argument  length                  3  Let len be ToUint32 lenValue               var len   O length  gt  gt  gt  0                 4  If len is 0  return -1              if  len     0                    return -1                               5  If argument fromIndex was passed let n be                   ToInteger fromIndex   else let n be 0              var n    fromIndex    0              if  Math abs n      Infinity                    n   0                               6  If n  gt   len  return -1              if  n  gt   len                    return -1                               7  If n  gt   0  then Let k be n                 8  Else  n lt 0  Let k be len - abs n                     If k is less than 0  then let k be 0              k   Math max n  gt   0   n   len - Math abs n   0                  9  Repeat  while k  lt  len             while  k  lt  len                       a  Let Pk be ToString k                        This is implicit for LHS operands of the in operator                    b  Let kPresent be the result of calling the                       HasProperty internal method of O with argument Pk                       This step can be combined with c                    c  If kPresent is true  then                       i   Let elementK be the result of calling the Get                           internal method of O with the argument ToString k                        ii   Let same be the result of applying the                           Strict Equality Comparison Algorithm to                           searchElement and elementK                      iii   If same is true  return k                  if  k in O  amp  amp  O k      searchElement                        return k                                    k                              return -1

User · Answer

The underscore js library has an indexOf function you can use instead     indexOf  1  2  3   2

User · Answer

With the Underscore js  var arr   a   a1   b      filter arr  function a   return a indexOf  a    gt  -1

User · Answer

The full code then would be this   if   Array prototype indexOf        Array prototype indexOf   function obj  start             for  var i    start    0   j   this length  i  lt  j  i                   if  this i      obj    return i                        return -1            For a really thorough answer and code to this as well as other array functions check out Stack Overflow question Fixing JavaScript Array functions in Internet Explorer  indexOf  forEach  etc

User · Answer

I would recommend this to anyone looking for missing functionality    http   code google com p ddr-ecma5   It brings in most of the missing ecma5 functionality to older browers

User · Answer

This was my implementation  Essentially  add this before any other scripts on the page  i e  in your master for a global solution for Internet Explorer 8  I also added in the trim function which seems to be used in allot of frameworks     lt  -- if lte IE 8  gt   lt script gt      if   Array prototype indexOf            Array prototype indexOf   function obj  start                for  var i    start    0   j   this length  i  lt  j  i                      if  this i      obj                        return i                                              return -1                        if typeof String prototype trim      function             String prototype trim   function                 return this replace    s   s   g                          lt  script gt   lt   endif -- gt

User · Answer

it works for me   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

[javascript] How to fix Array indexOf() in JavaScript for Internet Explorer browsers

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