javascript - Is there a known workaround for IE9's execution order of injected script tags? - Stack Overflow

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I am sure I don't fully understand this problem, but it seems that we are seeing strange behavior on IE9 on my project, somehow related to out-of-order execution of JavaScript that has been injected via calls to document.write, e.g.:

document.write('<scr'+'ipt type="text/javascript" src="'+file1+'"></src'+'ipt>');
document.write('<scr'+'ipt type="text/javascript" src="'+file2+'"></src'+'ipt>');
document.write('<scr'+'ipt type="text/javascript" src="'+file3+'"></src'+'ipt>');

My limited Google research suggests that IE9 will execute scripts injected in this manner in a different order from other browsers (notably, Firefox and Chrome). Is there a better way to achieve what we're going for here, which will ensure the same execution order by all browsers?

I take that back: we don't really care about all browsers, just Chrome and IE9.

I am sure I don't fully understand this problem, but it seems that we are seeing strange behavior on IE9 on my project, somehow related to out-of-order execution of JavaScript that has been injected via calls to document.write, e.g.:

document.write('<scr'+'ipt type="text/javascript" src="'+file1+'"></src'+'ipt>');
document.write('<scr'+'ipt type="text/javascript" src="'+file2+'"></src'+'ipt>');
document.write('<scr'+'ipt type="text/javascript" src="'+file3+'"></src'+'ipt>');

My limited Google research suggests that IE9 will execute scripts injected in this manner in a different order from other browsers (notably, Firefox and Chrome). Is there a better way to achieve what we're going for here, which will ensure the same execution order by all browsers?

I take that back: we don't really care about all browsers, just Chrome and IE9.

• javascript
• internet-explorer
• google-chrome
• labjs
• javascript-injection

Share Improve this question Follow edited Aug 22, 2011 at 21:09 user228852 asked Aug 19, 2011 at 19:11 Dan TaoDan Tao 128k5757 gold badges308308 silver badges450450 bronze badges 4

• (Thinking out loud): I wonder if inserting a script into the DOM with document.write() in IE9 is a non-blocking operation? – Russ Cam Commented Aug 19, 2011 at 19:13
• 1 (Also thinking out loud): Would it be possible to add a defer attribute to every injected tag? I've no idea what effect, if any, it'll have, but if the scripts are currently being evaluated in the order they finish downloading (i.e. smallest/quickest host first) instead of the order they're declared, adding defer might force them to stack. Maybe. – Flambino Commented Aug 19, 2011 at 19:20
• I'm sure it is. It is a widely accepted solution to non-blocking JavaScript calls. – Robin Winslow Commented Aug 19, 2011 at 19:20
• @Flambino: I don't know much about the defer attribute, but I actually did try that already and it didn't seem to fix the problem. – Dan Tao Commented Aug 19, 2011 at 19:36

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4 Answers 4

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Use a script loader (like the one I wrote: LABjs), which will normalize all the different quirks of loading across the various browsers. And bonus: it doesn't use that god-awful document.write(). LABjs will let you load all your scripts asynchronously (in parallel), but make sure they execute in the proper order. Sounds like basically exactly what you want.

I guess you could chain the onload event of one to start the load of another:

var newJS= document.createElement('script');
newJS.onload=function() {alert("done")} //or call next load function
newJS.src="..."
document.body.appendChild(newJS)

So the advantage of writing script tags this way is that they are loaded asynchronously. I don't know about browser nuances about exactly how this is done but I would have thought they would be executed when they're downloaded, in no specific order. Similar to the behaviour of the HTML5 async attribute.

There's another HTML5 attribute defer which instead makes scripts execute in order, but in a non blocking way. You could try adding that into your generated <script> tags. IE9 partially honours it.

I have made a little script, exactly for this purpose:

https://github./mudroljub/js-async-loader

In short, it loads all your scripts asynchronously, and then executes them consequently. It looks something like this:

for (var lib in libs) {
    loadAsync(lib);
}

And you don't need document.write();

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