What are the typical reasons Javascript developed on Firefox fails on IE? [closed]

Answer 1

IE is not a modern browser and only follows ECMAScript loosely.

Answer 2

There are loads of things, but one trap I used to fall in was that many browsers accepts JSON without quoted names, while ie6 and ie7 does not.

{ name: "Jakob" } // will often work, but not in ie6/ie7
{ "name": "Jakob" } // Better!

Edit: To clarify, this is only an issue when actual JSON is required, as opposed to an object literal. JSON is a subset of the object literal syntax and is meant as a data exchange format (like XML) which is why it's designed to be pickier.

Answer 3

For what it's worth I just came across this nasty issue in < IE9

say you have some html like this:

<table><tr><td>some content...</td></tr></table>

and for some reason (I had a good one) you need to retrieve all HTML in the table before the last closing TR you might try something like this:

var tableHtml = document.getElementById('thetable').innerHTML;
var fragment = tableHtml.substring(0, tableHtml.lastIndexOf('</tr>'));

< IE9 will return nothing (-1) here because the tableHtml variable contains all html tags upper-cased and lastIndexOf is case sensitive. To get around this I had to throw in a toLowerCase() before lastIndexOf.

Answer 4

The fact is that IE doesn't support JavaScript... It supports his own implementation of ECMAScript : JScript... which is kind of different...

Answer 5

I just found one this morning, a co-worker set the script tag as: <script type="application/javascript"> because his ide autocomplete had that before "text/javascript"

But, it turns out that IE just ignores the entire script if you use "application/javascript", you need to use "text/javascript"

Answer 6

You mentioned jQuery which I'm less familiar with but for general reference, and specifically with Prototype, one thing to watch out for is reserved words / method names in IE. I know what often gets me is things like:

someElement.appendChild(new Element('label',{ **for**: someInput.id }).update( someLabelText );

(new Element(tagName, propertyHash) is how new elements are created in Protitype). In IE, for: must be 'for':, because for is a reserved word. Which makes complete sense -- but FireFox will tolerate this.

Another example:

someElement.wrap('div').addClassName('someClass')

(the wrap method in Prototype wraps one element in another) -- In IE, on textareas, wrap is a property, and Element.wrap() must be used instead of the methodized version

These are two examples which come to mind from my experience. They're based on prototype but the core issue isn't: Watch out for any methods/labels/identifiers which IE considers reserved words but FireFox or Safari will tolerate.