loading js files and other dependent js files asynchronously
Solution 1
LabJS and RequireJS are two popular choices right now. They both work with jQuery but take slightly different approaches, so you should look at both.
Solution 2
LABjs is made specifically for this problem.
<script src="lab.js"></script>
<script>
$LAB
.script("jquery.js")
.wait()
.script("jquery.color.js")
.script("jquery.otherplugin.js")
.script("mylib.js")
.wait()
.script("unrelated1.js")
.script("unrelated2.js");
</script>
You could also put the unrelated scripts into their own $LAB
chain, if they really have no need to wait for jQuery and your other scripts.
Solution 3
You can leverage the YUI Loader to register your own modules and dependencies and then load them.
You get complete hooks for success, failure, and even progress, so you can hook any asynchronous action you like.
Related videos on Youtube
Comments
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taber about 2 years
I'm looking for a clean way to asynchronously load the following types of javascript files: a "core" js file (hmm, let's just call it, oh i don't know, "jquery!" haha), x number of js files that are dependent on the "core" js file being loaded, and y number of other unrelated js files. I have a couple ideas of how to go about it, but not sure what the best way is. I'd like to avoid loading scripts in the document body.
So for example, I want the following 4 javascript files to load asynchronously, appropriately named:
/js/my-contact-page-js-functions.js // unrelated/independent script /js/jquery-1.3.2.min.js // the "core" script /js/jquery.color.min.js // dependent on jquery being loaded http://thirdparty.com/js/third-party-tracking-script.js // another unrelated/independent script
But this won't work because it's not guaranteed that jQuery is loaded before the color plugin...
(function() { var a=[ '/js/my-contact-page-functions.js', '/js/jquery-1.4.2.min.js', '/js/jquery.color.js', 'http://cdn.thirdparty.com/third-party-tracking-script.js', ], d=document, h=d.getElementsByTagName('head')[0], s, i, l=a.length; for(i=0;i<l;i++){ s=d.createElement('script'); s.type='text/javascript'; s.async=true; s.src=a[i]; h.appendChild(s); } })();
Is it pretty much not possible to load jquery and the color plugin asynchronously? (Since the color plugin requires that jQuery is loaded first.)
The first method I was considering is to just combine the color plugin script with jQuery source into one file.
Then another idea I had was loading the color plugin like so:
$(window).ready(function() { $.getScript("/js/jquery.color.js"); });
Anyone have any thoughts on how you'd go about this? Thanks!
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taber almost 14 yearsthanks, if i wanted to load lab.js asynchronously too, how would i know when $LAB exists and is ready to be called? would i need to use something like: function initLab(){ ... } ... document.onload = initLab;
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bcherry almost 14 yearsYou could do something like that, but I'd advise against it. LAB.js is only 4.5k after minification (only 2.1k across the wire gzipped). If you wanted, you could inline the LABjs code into a
<script>
tag in the HTML document, but loading as a synchronous<script src>
should be fine at its size. -
taber almost 14 yearsah-ha, and i can pass .wait() an anonymous function to postpone init routines etc. until the previous js files have loaded. awesome, thanks.
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msanford almost 12 years@taber Mining an old thread, the site's been updated to include Snippet to load LABjs itself dynamically gist.github.com/603980
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jk jk over 10 yearsthis method need to use <script> tag to link a js file, not inline script, also require a load script plugin
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taber over 7 yearsLAB seems to no longer be maintained, so I changed the accepted answer to yours, since you mentioned RequireJS. (Probably a better choice nowadays!) Hopefully this is the "right" thing to do for older questions here on SO.
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chovy about 3 yearsis there a new es6+ way to do this with
async
anddefer
? -
ndp about 3 yearsThere are several modern ways to do this, and
async
anddefer
are two good tools to be aware of. It seems like the tools like webpack and requirejs call this feature "on-demand chunk loading", so you can look for that.