Working together for standards The Web Standards Project

IE7 JavaScript Improvements

By Dean Edwards | September 21st, 2006 | Filed in Browsers, DOM Scripting TF, Microsoft, Microsoft TF

The IEBlog recently reported some improvements in IE7’s JavaScript engine.

Skip to comment form

The IEBlog recently reported some improvements
in IE7’s JavaScript engine:

We have heard a lot of requests to improve our Jscript engine, especially now that AJAX
sites are becoming more prevalent on the web. I want you all to know that we have been
listening and have recently made some great fixes to our engine to improve the garbage
collection routine and to reduce unbounded memory growth.

This was confirmed by tests performed by the qooxdoo developers:

In fact many demos of qooxdoo
run much faster now in IE7 compared to IE6. And they are even faster than in Firefox 1.5 in many cases.
This is a huge jump in performance. Microsoft did not tell about their exact modifications, of course.
Anyway, they have fixed the major problem of large JavaScript-based web applications. This problem,
despite having a catchy name, was mentioned many times before like
here and
If you have many objects created, which are simply accessible in the current scope, all
methods and features of JavaScript slow down dramatically.

It would be great if these bugs were fixed so I emailed
Chris Wilson for comfirmation. He replied:

Yes, it is true we’ve done some dramatic improvements to JavaScript
performance. I wouldn’t say we’ve fixed everything, but we’ve addressed
a bunch of memory leak problems and most significantly, taken a
different strategy for the Jscript garbage collector. This last one
makes a huge difference in many current JavaScript-heavy pages.

Good news indeed.

Your Replies

#1 On September 21st, 2006 11:18 am George replied:

Good news indeed. I’m really impressed with IE7 – it will make a huge difference when it is released. Standards compliance, a great rendering engine and better Javascript are really exciting.

#2 On September 21st, 2006 6:29 pm Pig Pen - Web Standards Compliant Web Design Blog » Blog Archive » IE7 JavaScript Improvements replied:

[...] IE7 JavaScript Improvements is interesting to mention. [...]

#3 On September 22nd, 2006 12:42 am me replied:

There is still a lot to be done though. e.g. prototypes on Object extensions on HtmlElement

#4 On September 22nd, 2006 2:01 am Robert replied:

While certainely true that this is very good news, do not forget that we already have browsers with all these features. So, it’s still a game of catch-up for IE.

#5 On September 22nd, 2006 2:41 am NiQuil replied:

Ie7 is a huge improvement, I wonder though if it will actually make programmers work easyer in th NEAR future. Since they still will have maintain backwards compatibility.

#6 On September 22nd, 2006 5:27 am Jake Archibald replied:

If you rate IE7 compared to Firefox / Opera, then yes it’s nothing special.

If you rate IE7 compared to IE6 it’s a huge leap forward.

Really happy with the improvements they’ve made and hope there’s more to come. Recently been designing a new CV site there’s been very little in the way of specific IE7 fixes. Still have to have an additional css for IE6 and below, but at least that will eventually become a thing of the past.

#7 On September 24th, 2006 3:36 pm Ollie replied:

Although we should all be happy because (a lot of us) are web designers and developers, maybe we shouldn’t be happy because Microsoft is just putting bugs right that should have never existed in the first place!

#8 On September 25th, 2006 6:36 am RazorX replied:

While it is nice that IE 7 has performance and standards improvements in the JScript engine, it’s catch-up arrival is late in the game. JScript (JavaScript) itself is still a client-side “convenience” script. Your good designers are using less and less JavaScript in favor of server-side scripting in every new design. The future trend, mostly based on a culminating increase in data reliance and security, is to use none, or as little JavaScript as possible. If JavaScript is turned off, your web site and your forms better still work without it.

#9 On September 30th, 2006 11:06 am Asp_net_2_0_Rocks replied:

really good support for Jscript. but it doesnt get easy on developers they will still need to keep up with prior versions since market wont switch to IE7 quickly.

#10 On October 7th, 2006 1:21 pm rick replied:

When reading some replies I am very doubtful if these are real improvements. See for example this reply:

#11 On October 9th, 2006 4:53 am pedja replied:

javascript in IE7 RC1 still does not work well for me. Actualy, some javascript that can be executed with the IE7 beta 2 does not work in IE7 RC1.
One of my major problems with the IE& is that I still cannot use properly an old MSDN Library for Visual Studio 6.0 since many links in it execute some javascript which can’t be run with IE7.

#12 On October 21st, 2006 7:02 am vHoward replied:

‘Your good designers are using less and less JavaScript in favor of server-side scripting in every new design.’

On the contary, javascript has had a fresh lease of life, enabling a whole range of web apps that owe there snappy performance and rich featureset to ajax style scripting.

After all lower server hits can only be a good thing, unless you’re in the ad sales game!

Lets hope that IE7 js really does banish the sluggish performance and soul destroying memory leaks that developers have had to fight with IE6.

#13 On November 28th, 2006 9:41 am Peter replied:

I have been looking at IE7 and in many ways it seems better, but I have a major problem with the way it is implementing JavaScript arrrays.

I have an old application that holds data in a large Javascript array. This has always worked fine.

However, in IE7 it falls over. It seems like it is just falling over when an array gets too big.

Has anyone else come across this problem or any related problem with IE7.

I have been hunting around and cannot find any reference to an upper limit to array sizes in JavaScript.

#14 On December 21st, 2006 4:25 pm Bob replied:

As Peter stated I’ve discovered the same issue with Javascript array sizes. Code that has run fine pre IE7 now fails. I’m curious if a solution is available. I’m in agreement that with the advent and growth of AJAX and it’s dynamic capabilities, imposing limits on Javascript within the browser is a step backwards.

Return to top

Post a Reply

Comments are closed.

All of the entries posted in WaSP Buzz express the opinions of their individual authors. They do not necessarily reflect the plans or positions of the Web Standards Project as a group.

This site is valid XHTML 1.0 Strict, CSS | Get Buzz via RSS or Atom | Colophon | Legal