Dynamically load a JavaScript file

Question

How can you reliably and dynamically load a JavaScript file? This will can be used to implement a module or component that when \'initialized\' the component will dynamical

Answer 1

Just found out about a great feature in YUI 3 (at the time of writing available in preview release). You can easily insert dependencies to YUI libraries and to "external" modules (what you are looking for) without too much code: YUI Loader.

It also answers your second question regarding the function being called as soon as the external module is loaded.

Example:

YUI({
    modules: {
        'simple': {
            fullpath: "http://example.com/public/js/simple.js"
        },
        'complicated': {
            fullpath: "http://example.com/public/js/complicated.js"
            requires: ['simple']  // <-- dependency to 'simple' module
        }
    },
    timeout: 10000
}).use('complicated', function(Y, result) {
    // called as soon as 'complicated' is loaded
    if (!result.success) {
        // loading failed, or timeout
        handleError(result.msg);
    } else {
        // call a function that needs 'complicated'
        doSomethingComplicated(...);
    }
});

Worked perfectly for me and has the advantage of managing dependencies. Refer to the YUI documentation for an example with YUI 2 calendar.