前端性能优化四十二：模块化加载方案

1. JS模块化加载方案和选型:

①. CommonJS:
    a. 旨在Web浏览器之外为JavaScript建立模块生态系统,同步加载.
    b. Node.js模块化方案受CommonJS影响,非常类似.

②. AMD(Asynchronous Module Definition):
    a. 异步模块定义规范,主要应用于浏览器上.
    b. RequireJS模块化加载器:
       (1). 基于AMD API实现

③. CMD(Common Module Definition):
    a. 通用模块定义规范
    b. SeaJS模块化加载器:
       (1). 遵循CMD API编写

④. ES6 import:

(1). CommonJs:

var store = require('store')
exports = function() {
    return store.get('customers')
}

(2). NodeJS module:

var store = require('store')
function customerStore() {
    return store.get('customers')
}
modules.exports = customerStore

(3). RequestJs:

<script data-main="script/main" src="scripts/require.js"></script>

(4). SeaJS:

define(function(require, exports, module) {
})
define('module', ['module1', 'module2'], function(require, exports, module) {
})