Prevent RequireJS from Caching Required Scripts

RequireJS seems to do something internally that caches required javascript files. If I make a change to one of the required files, I have to rename the file in order for the changes to be applied.

The common trick of appending a version number as a querystring param to the end of the filename does not work with requirejs <script src="jsfile.js?v2"></script>

What I am looking for is a way to prevent this internal cacheing of RequireJS required scripts without having to rename my script files every time they are updated.

Cross-Platform Solution:

I am now using urlArgs: "bust=" + (new Date()).getTime() for automatic cache-busting during development and urlArgs: "bust=v2" for production where I increment the hard-coded version num after rolling out an updated required script.

Note:

@Dustin Getz mentioned in a recent answer that Chrome Developer Tools will drop breakpoints during debugging when Javascript files are continuously refreshed like this. One workaround is to write debugger; in code to trigger a breakpoint in most Javascript debuggers.

Server-Specific Solutions:

For specific solutions that may work better for your server environment such as Node or Apache, see some of the answers below.

RequireJS can be configured to append a value to each of the script urls for cache busting.

From the RequireJS documentation (http://requirejs.org/docs/api.html#config):

urlArgs: Extra query string arguments appended to URLs that RequireJS uses to fetch resources. Most useful to cache bust when the browser or server is not configured correctly.

Example, appending "v2" to all scripts:

require.config({
    urlArgs: "bust=v2"
});

For development purposes, you can force RequireJS to bypass the cache by appending a timestamp:

require.config({
    urlArgs: "bust=" + (new Date()).getTime()
});

Do not use urlArgs for this!

Require script loads respect http caching headers. (Scripts are loaded with a dynamically inserted <script>, which means the request looks just like any old asset getting loaded.)

Serve your javascript assets with the proper HTTP headers to disable caching during development.

Using require's urlArgs means any breakpoints you set will not be preserved across refreshes; you end up needing to put debugger statements everywhere in your code. Bad. I use urlArgs for cache-busting assets during production upgrades with the git sha; then I can set my assets to be cached forever and be guaranteed to never have stale assets.

In development, I mock all ajax requests with a complex mockjax configuration, then I can serve my app in javascript-only mode with a 10 line python http server with all caching turned off. This has scaled up for me to a quite large "enterprisey" application with hundreds of restful webservice endpoints. We even have a contracted designer who can work with our real production codebase without giving him access to our backend code.