Underscore.js 是一个 JavaScript 工具库它提供了一整套函数式编程的实用功能但是没有扩展任何 JavaScript 内置对象。Underscore 提供了100多个函数优化方案但是没有扩展任何 JavaScript 内置对象。Underscore 提供了100多个函数包括常用的：map、filter、invoke — 当然还有更多专业的辅助函数如：函数绑定、JavaScript 模板功能、创建快速索引、强类型相等测试等等。 微信小程序无法直接使用require( 'underscore.js' )进行调用。
微信小程序模块化机制微信小程序运行环境支持CommoJS模块化通过module.exports暴露对象通过require来获取对象。
微信小程序Quick Start utils/util.js
function formatTime(date) { var year = date.getFullYear() var month = date.getMonth() + 1 var day = date.getDate() var hour = date.getHours() var minute = date.getMinutes() var second = date.getSeconds(); return [year, month, day].map(formatNumber).join('/') + ' ' + [hour, minute, second].map(formatNumber).join(':') } function formatNumber(n) { n = n.toString() return n[1] ? n : '0' + n } module.exports = { formatTime: formatTime } pages/log/log.js var util = require('../../utils/util.js') Page({ data: { logs: [] }, onLoad: function () { this.setData({ logs: (wx.getStorageSync('logs') || []).map(function (log) { return util.formatTime(new Date(log)) }) }) } })Underscore CommonJs模块导出代码如下：
// Export the Underscore object for **Node.js**, with // backwards-compatibility for the old `require()` API. If we're in // the browser, add `_` as a global object. if (typeof exports !== 'undefined') { if (typeof module !== 'undefined' && module.exports) { exports = module.exports = _; } exports._ = _; } else { root._ = _; }exports、module必须都有定义才能导出。通过测试微信小程序运行环境exports、module并没有定义
//index.js //获取应用实例 var app = getApp(); Page({ onLoad: function () { console.log('onLoad'); var that = this; console.log('typeof exports: ' + typeof exports); console.log('typeof module: ' + typeof exports); var MyClass = function() { } module.exports = MyClass; console.log('typeof module.exports: ' + typeof module.exports); } })修改Underscore代码注释原有模块导出语句使用module.exports = _ 强制导出
/* // Export the Underscore object for **Node.js**, with // backwards-compatibility for the old `require()` API. If we're in // the browser, add `_` as a global object. if (typeof exports !== 'undefined') { if (typeof module !== 'undefined' && module.exports) { exports = module.exports = _; } exports._ = _; } else { root._ = _; } */ module.exports = _; /* // AMD registration happens at the end for compatibility with AMD loaders // that may not enforce next-turn semantics on modules. Even though general // practice for AMD registration is to be anonymous, underscore registers // as a named module because, like jQuery, it is a base library that is // popular enough to be bundled in a third party lib, but not be part of // an AMD load request. Those cases could generate an error when an // anonymous define() is called outside of a loader request. if (typeof define === 'function' && define.amd) { define('underscore', [], function() { return _; }); } */