Using Javascript to load other external Javascripts

Question

I have a library of JS code to load from a folder. Instead of typing the <script src='...'></script> lines one by one in the tag of the HTML document, is there a way of just link one Javascript file which organizes and automatically load other javascript files.

I know the Dojotoolkit is using this technique where only one JS file is loaded onto the client's computer, and once the code has been requested in the browser, 20 other JS code each with <script> tag are generated.

• Pointy: Google for LabJS and RequireJS.
• ankitjaininfo: duplicate: stackoverflow.com/questions/21294/…
• balupton: Not duplicate, other question is for the Prototype framework. This one is for vanilla javascript.

Answer 1

This is the code you need:

 // Create
 var bodyEl = document.body;
 var scriptEl = document.createElement('script');
 scriptEl.type = 'text/javascript';
 scriptEl.src = url;
 bodyEl.appendChild(scriptEl);

Put that into a function, have an array of all the javascript files, and call that function for each file.

Benefits of using the DOM is that document.write doesn't work in some funny instances. More about this here: document.write() vs inserting DOM nodes: preserve form information?

Code taken from the open source project jQuery Sparkle: http://github.com/balupton/jquery-sparkle/blob/master/scripts/resources/jquery.appendscriptstyle.js#L103

• Pointy: It's not necessary to set the "type" attribute.
• balupton: @Pointy while it will work without it, it is still a required attribute: w3schools.com/TAGS/tag_script.asp and google.com.au/…
• Pointy: Most contemporary Javascript experts (Doug Crockford in particular) encourage omission of the attribute, and it's explicitly not needed in HTML5. Besides that, the HTML spec is irrelevant when you're building DOM nodes.
• Dennis D: will this sacrifice loading time? Is using prototype faster?
• Josh: @Pointy: I'd love to read what Doug had to say on that topic as I also always include the type attribute for completeness.

Answer 2

A simple way to do that:

document.write("<script type='text/javascript' src='b.js'></script>"); 

• Pointy: Using document.write is generally strongly deprecated. The same effect can be achieved by adding a <script> tag to the document.
• user333306: Valid, but I like it's simplicity and it's low characters consumption.
• Tim Down: document.write isn't deprecated. It's in the HTML 5 spec for a start: w3.org/TR/html5/embedded-content-0.html#dom-document-write
• Tim Down: Also, adding a <script> element to the document does not have the same effect: using document.write is synchronous (as is including a <script> element in HTML) while adding a <script> element using DOM methods is asynchronous. The synchronous approach has advantages, for example being guaranteed to have loaded before scripts that appear after it in the document.

Answer 3

Try use requireJs, he have very userful functions

Official website