javascript - 简化的 commonJS 包装器如何在 require.js 中工作？

Question

考虑他们网站上的这个例子

define(function (require) {
    var foo = require('foo');

    //Define this module as exporting a function
    return function () {
        foo.doSomething();
    };
});

我的问题是，由于“foo”是异步加载的，它下面的 Javascript 如何在加载之前不执行？

Answer 1

这在 http://requirejs.org/docs/api.html#cjsmodule 中有解释和 http://requirejs.org/docs/whyamd.html#sugar .

Require.js 会在某个时候(在运行函数之前)查看函数的字符串表示，找到所有require 调用以确定依赖项并加载它们.

To make this easier, and to make it easy to do a simple wrapping around CommonJS modules, this form of define is supported, sometimes referred to as "simplified CommonJS wrapping":

define(function (require) {
    var dependency1 = require('dependency1'),
        dependency2 = require('dependency2'); 
    return function () {};
});

The AMD loader will parse out the require('') calls by using Function.prototype.toString(), then internally convert the above define call into this:

define(['require', 'dependency1', 'dependency2'], function (require) {
    var dependency1 = require('dependency1'),
        dependency2 = require('dependency2');
    return function () {};
});

This allows the loader to load dependency1 and dependency2 asynchronously, execute those dependencies, then execute this function.