player/js/utils/asset_loader.js

var assetLoader = (function(){

	function formatResponse(xhr) {
		if(xhr.response && typeof xhr.response === 'object') {
			return xhr.response;
		} else if(xhr.response && typeof xhr.response === 'string') {
			return JSON.parse(xhr.response);
		} else if(xhr.responseText) {
			return JSON.parse(xhr.response);
		}
	}

	function loadAsset(path, callback, errorCallback) {
		var response;
		var xhr = new XMLHttpRequest();
		xhr.open('GET', path, true);
		// set responseType after calling open or IE will break.
		xhr.responseType = "json";
	    xhr.send();
	    xhr.onreadystatechange = function () {
	        if (xhr.readyState == 4) {
	            if(xhr.status == 200){
	            	response = formatResponse(xhr);
	            	callback(response);
	            }else{
	                try{
	            		response = formatResponse(xhr);
	            		callback(response);
	                }catch(err){
	                	if(errorCallback) {
	                		errorCallback(err);
	                	}
	                }
	            }
	        }
	    };
	}
	return {
		load: loadAsset
	}
}())