下面是个require.js，我们项目（一个ionic项目）里用到的，google得到的信息也不多。
上网查了一下，得知有什么nodejs按照CommonJS实现的requirejs，还有AMD规范的requirejs，但是我们项目里用的是下面的这个require.js，用法和AMD的写法不一样，和nodejs的比较像，而且用gulp也能对这个进行打包，我想问问这到的是个什么东西，还有它说是Smoothie的一部分，不知道这个Smoothie是个什么项目。兼容性貌似也不是很好，Android5.0以下是不支持这玩意的，如果我想兼容个IE8(或者放宽到IE9也行)什么的，在浏览器的环境下有什么requireJS能够供我选择呢？

//
// This file is part of Smoothie.
//
// Copyright (C) 2013-2015 Flowy Apps GmbH 
//
// Smoothie is free software: you can redistribute it and/or modify it under the
// terms of the GNU Lesser General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option) any
// later version.
//
// Smoothie is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
// A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
// details.You should have received a copy of the GNU Lesser General Public
// License along with Smoothie.  If not, see .
//
////////////////////////////////////////////////////////////////////////////////

// INFO Standalone require()
//      This is a stripped down standalone version of Smoothie's require
//      function. If you also like to have a 'bootloader', which gives you some
//      nice hooks to execute code on different loading states of the document
//      and keeps your JavaScript completely separate from your HTML, we
//      recommend to load smoothie.js from the library's root directory.

// NOTE The load parameter points to the function, which prepares the
//      environment for each module and runs its code. Scroll down to the end of
//      the file to see the function definition.
(function(load) { 'use strict';

var SmoothieError = function(message, fileName, lineNumber) {
    this.name = "SmoothieError";
    this.message = message;
}
SmoothieError.prototype = Object.create(Error.prototype);

// NOTE Mozilla still sets the wrong fileName porperty for errors that occur
//      inside an eval call (even with sourceURL). However, the stack
//      contains the correct source, so it can be used to re-threw the error
//      with the correct fileName property.
// NOTE Re-threwing a new error object will mess up the stack trace and the
//      column number.
if (typeof (new Error()).fileName == "string") {
    self.addEventListener("error", function(evt) {
        if (evt.error instanceof Error) {
            if (pwd[0]) {
                evt.preventDefault();
                throw new evt.error.constructor(evt.error.message, pwd[0].uri, evt.error.lineNumber);
            }
            else {
                var m = evt.error.stack.match(/^[^\n@]*@([^\n]+):\d+:\d+/);
                if (m === null) {
                    console.warn("Smoothie: unable to read file name from stack");
                }
                else if (evt.error.fileName != m[1]) {
                    evt.preventDefault();
                    throw new evt.error.constructor(evt.error.message, m[1], evt.error.lineNumber);
                }
            }
        }
    }, false);
}

// INFO Current module descriptors
//      pwd[0] contains the descriptor of the currently loaded module,
//      pwd[1] contains the descriptor its parent module and so on.

var pwd = Array();

// INFO Path parser
// NOTE Older browsers don't support the URL interface, therefore we use an
//      anchor element as parser in that case. Thes breaks web worker support,
//      but we don't care since these browser also don't support web workers.

var parser = URL ? new URL(location.href) : document.createElement('A');

// INFO Module cache
// NOTE Contains getter functions for the exports objects of all the loaded
//      modules. The getter for the module 'mymod' is name '$name' to prevent
//      collisions with predefined object properties (see note below).
//      As long as a module has not been loaded the getter is either undefined
//      or contains the module code as a function (in case the module has been
//      pre-loaded in a bundle).
// NOTE IE8 supports defineProperty only for DOM objects, therfore we use a
//      HTMLpElement as cache in that case. This breaks web worker support,
//      but we don't care since IE8 has no web workers at all.

try {
    var cache = new Object();
    Object.defineProperty(cache, "foo", {'value':"bar",'configurable':true});
    delete cache.foo;
}
catch (e) {
    console.warn("Falling back to DOM workaround for defineProperty: "+e);
    cache = document.createElement('p');
}

// INFO Send lock
// NOTE Sending the request causes the event loop to continue. Therefore
//      pending AJAX load events for the same url might be executed before
//      the synchronous onLoad is called. This should be no problem, but in
//      Chrome the responseText of the sneaked in load events will be empty.
//      Therefore we have to lock the loading while executing send().   

var lock = new Object();

// INFO Smoothie options
//      The values can be set by defining a object called Smoothie. The
//      Smoothe object has to be defined before this script here is loaded
//      and changing the values in the Smoothie object will have no effect
//      afterwards!

var requirePath = self.Smoothie&&self.Smoothie.requirePath!==undefined ? self.Smoothie.requirePath.slice(0) : ['./'];
var requireCompiler = self.Smoothie&&self.Smoothie.requireCompiler!==undefined ? self.Smoothie.requireCompiler : null;

// NOTE Parse module root paths
var base = [location.origin, location.href.substr(0, location.href.lastIndexOf("/")+1)];
for (var i=0; i