require.js in browser

require.js

/**
* Require stub for browser.
* Prepend this script in head.
* Set `data-module="name"` attribute on script tag to define module name to register (or it will be parsed as src file name).
* Works only in browsers supporting Object.observe (Chrome with flags)
*/

//module/exports changing observer to expose global variables
var module = {};
var exports = {};

var modules = {};
var modulePaths = {};

//stupid require stub
function require(name){
	// console.log('require', name+'.js', modulePaths[name+'.js'])
	return modules[name] || modules[modulePaths[name]] || modules[modulePaths[name+'.js']];
}

Object.observe(module, function(changes){
	for (var i = changes.length; i--;){
		var change = changes[i];
		if (change.name === "exports" && change.type === "add"){
			var exports = change.object.exports;
			var script = document.currentScript;

			//ignore inline scripts
			if (!document.currentScript.src) return;

			//parse module name
			var moduleName = script.getAttribute('data-module');
			if (!moduleName) {
				moduleName = script.getAttribute('src');

				//clear name
				moduleName = moduleName.split(/[\\\/]/).pop().split('.').shift();
			}

			//save module path
			modulePaths[script.src] = moduleName;
			modulePaths[script.getAttribute('src')] = moduleName;

			//expose module to modules list (in order to get by require)
			modules[moduleName] = exports;
			delete module.exports;
		}
	}

	Object.observe(exports, function(){
		//TODO: save exports changes to current module
	})

	//TODO: listen to `onbeforescriptexecute` on Firefox.
});