A couple of days ago, I had to create some web application with a very rich client side UI.
It worked like a charm in Google Chrome, Firefox… but IE7, after few dozens of nyroModal popups it just went dead.

Most of the styles are gone, JavaScript functions began to throw exceptions till it just stoped working, decided it can’t tolerate this kind of abuse any more and closed it self without any warning.

The first thing i did is to open Performance Monitor and what I see… every nyroModal popup i open cost me about 5Mb, so after a few clicks my IE7 virtual memory was about 789Mb. Terrifying, isn’t it ?

I’ve searched a bit and found the source of this problem was in one (of many) memory leaks IE7 proudly has – cleaning memory for removed HTML elements.

And now the fix.

1). Open your jQuery.js and find the next lines of code

    jQuery.extend({
        cache: {},

and add new function “discardElement”

    jQuery.extend({
        cache: {},

        discardElement: function(element) {
            var jqGCID = 'jqGarbageCollector';
            var jqGC = document.getElementById(jqGCID);
            if (!jqGC) {
                jqGC = document.createElement('div');
                jqGC.id = jqGCID;
                jqGC.style.display = 'none';
                document.body.appendChild(jqGC);
            }

            // place the element to the Garbage Collector
            // and clear it's HTML contents
            jqGC.appendChild(element);
            jqGC.innerHTML = '';
        },

2). Find the next lines of code in the opened jquery.js

	remove: function( selector ) {
		if ( !selector || jQuery.filter( selector, [ this ] ).length ) {
			// Prevent memory leaks
			jQuery( "*", this ).add([this]).each(function(){
				jQuery.event.remove(this);
				jQuery.removeData(this);
			});
			if (this.parentNode)
				this.parentNode.removeChild( this );
		}
	},

and replace “this.parentNode.removeChild( this );”
with “jQuery.discardElement(this);”

	remove: function( selector ) {
		if ( !selector || jQuery.filter( selector, [ this ] ).length ) {
			// Prevent memory leaks
			jQuery( "*", this ).add([this]).each(function(){
				jQuery.event.remove(this);
				jQuery.removeData(this);
			});
			if (this.parentNode)
				// this.parentNode.removeChild( this );
				jQuery.discardElement(this);
		}
	},

That’s it, now you (and every plugin) can do $(‘element’).remove() without being worry IE will eat all of your memory.

IETester is a free WebBrowser that allows you to have the rendering and javascript engines of IE8, IE7 IE 6 and IE5.5 on Vista and XP, as well as the installed IE in the same process.

Despite some little bugs IETester is a very nice tool and for my opinion this is a must for any web developer who makes cross browser web sites and don’t want to install virtual server for each IE version.

Coming soon…