YUI seed loader

loader.js

/**
 * Light-weight YUI-dependend Script Loader
 * - loads YUI 3 if not already loaded
 * - then loads your script(s)
 *
 * Useful for dynamically loaded modules, injected scripts, bookmarklets, etc…
 */
(function() {

// YUI to load if unavailable 
var YUI_SRC = 'http://yui.yahooapis.com/combo?3.1.1/build/yui/yui-min.js' +
              '&3.1.1/build/loader/loader-min.js',

// scripts to load once YUI is available: a url or array of urls
SCRIPTS = ['http://example.com/script1.js', 'http://example.com/script2.js'];

function onYUIAvailable() {
    Y.Get.script(SCRIPTS);
}

if (typeof YUI === 'undefined') {
    YUI_config = {injected:true};
    var node = document.createElement('script'),
        head = document.documentElement.firstChild;
    node.type = 'text/javascript';
    if (node.readyState) {
        node.onreadystatechange = function() {
            if (node.readyState == 'loaded' || node.readyState == 'complete') {
                node.onreadystatechange = null;
                onYUIAvailable();
            }
        };
    } else {
        node.onload = onYUIAvailable;
    }
    node.src = YUI_SRC;
    head.insertBefore(node, head.firstChild);
} else {
    onYUIAvailable();
}

})();