indexOf in < IE9

[ldoodle]

IE8 reports indexOf is not a supported method. I'm using this to get the value of an array item.

However, MS say IE6+ should be supported; http://msdn.microsoft.com/en-us/libr...(v=vs.94).aspx

[bionoid]

All String objects/literals have a indexOf method, if you however passed in a number or boolean etc, then you will have to convert it to String() first:

alert(  'Test'.indexOf('e')  ); //1
alert(  String(123).indexOf('3')  ); //2

[ldoodle]

I am passing a string already;

j = b.indexOf(photoUrl);

with photoUrl being a parameter, such as /images/subfolder1/subfolder2/image.jpg

Maybe the / in the string are ****ing it up?

[bionoid]

But what is the value of "b", as that is where the problem would b ?

[Logic Ali]

IE8 reports indexOf is not a supported method. I'm using this to get the value of an array item.

However, MS say IE6+ should be supported; http://msdn.microsoft.com/en-us/library/53xtt423(v=vs.94).aspx

That article refers to String().indexOf not Array().indexOf which is of much more recent introduction.

Here's the crutchware that you need:

if( Array().indexOf === undefined )
{
  Array.prototype.indexOf = function( item )
  {
    for( var i = this.length - 1; i > -1 && this[ i ] !== item; i-- )
    ;
  
    return i;
  }
}

[ldoodle]

That article refers to String().indexOf not Array().indexOf which is of much more recent introduction.

Thankyou very much. I have seen other variants of your code but they didn't seem to work.



EDIT: I noticed yours uses triple = rather than double. Why? Also some of the other articles on the MS website use triple (http://msdn.microsoft.com/en-us/libr...155295(v=vs.94))

[Logic Ali]

I noticed yours uses triple = rather than double. Why? Also some of the other articles on the MS website use triple (http://msdn.microsoft.com/en-us/library/jj155295(v=vs.94))

Strict type checking is always good practice.

Actually I now realise that code isn't right, and having looked at the specs, the function allows an optional starting index to be used, so I re-wrote it:

Array.prototype.indexOf = Array.prototype.indexOf || function( item, idx )
{
  var retVal = 0,
      startIndex = ( typeof idx === 'number' ? Math.abs( Math.floor( idx ) ) : 0 );
       
  for( var i = startIndex, len = this.length; i < len && this[ i ] !== item; i++ )
  ;
  
  return i == len ? -1 : i;
}