/**
 *    @module
 *    @author daemon.devin <daemon.devin@gmail.com>
 *
 *    @param {String}   file - The path of the file you want to load.
 *    @param {Function} callback (optional) - Called after script load.
 */
var loader = loader || (Function() {
    return {
    	
    	load: function(file, callback) {

            var script = document.createElement('script');
            script.src = file, script.async = true;
            
  			// If defined, execute the callback after checking 
  			// if the script has been successfully loaded.
            if (callback !== undefined) {
            	
            	// IE calls `script.onreadystatechange()` continuously
            	// as the script loads. Use `script.onreadystatechange()`
            	// to check if the script has finished loading.
	        script.onreadystatechange = function() {
	                
	            // When the script finishes loading, IE sets 
	            // `script.readyState` to either 'loaded' or 'complete'.
	            if (script.readyState === 'loaded' ||
	                script.readyState === 'complete') {
	                    
                  	// Set `onreadystatechange()` to null to prevent 
                  	// it from firing again.
	                script.onreadystatechange = null;
	                    
	                // Execute the callback.
	                callback (file );
	            }
	        };
	            
	        // The following is one of the reasons IE is infereor
            // to all modern browsers.
	        script.onload = function () {
	            callback ( file );
	        };
            }
            
  			// Add the loaded script to the end of the document 
  			// so it won't hinder the rest of the page from loading.
            document.body.appendChild(script);
        } 
    };
}());