本书内容涵盖了 Node.js高并发的原理、源码分析以及使用 Node.js开发应用所需要的不同层面 的技术实践。具体来讲，本书包括 Node.js异步机制（配以源码分析）、编辑与调试、测试技术、 Docker 部署、模块机制、V8 引擎与代码优化、Promise 和 ES6 Generator、LoopBack 开源框架、使 用 C 编写扩展、JavaScript严格模式、编码规范等内容。在 LoopBack 章节，本书详细介绍了使 用此框架开发企业级 Web 应用的步骤，帮助读者迅速掌握使用这个强大框架的诀窍。*后一章详 细介绍了编写不同类型的 C 模块的知识，并对堆内存管理等内容做了深入探讨。 本书适合所有前端和后端的开发人员阅读。

一线Node开发者数年实战经验总结，适合所有前端和后端的开发人员阅读本书内容涵盖Node 高并发的原理、源码分析以及使用 Node 开发应用所需要的不同层面的技术实践。具体包括 Node 异步机制（配以源码分析），编辑与调试，测试技术，Docker 部署，模块机制，V8 引擎与代码优化，Promise 和 ES6 generator ，LoopBack 开源框架，使用 C 编写扩展，JavaScript 严格模式，编码规范等内容。

前 言
本书写给那些打算或者正在使用 Node.js（简称Node，后文均用此简称）创建 Web 应用的开发者。众所周知，JavaScript 的灵活易用以及 V8 引擎的加速，再加上活跃的社区支持，使得用 Node 开发应用的成本低，收益大。2015 年 ES6 标准的确立，为JavaScript成为企业级开发语言扫除了不确定性。这本书的选材契合这个领域最新的技术进展，深浅适宜地介绍了 Node 技术栈的全貌。
本书共分9章。第1章概述，介绍 Node 异步实现的原理，涵盖了 Node 实现异步的两种方式。这部分引用了 Node 源码，以求逻辑清晰与内容翔实。第2章～第7章是站在JavaScript 的角度，介绍了用 Node 开发应用的方方面面，包括编辑与调试、测试技术、Docker 部署、模块机制、V8 引擎与代码优化、Promise 和 ES6 generator 等内容。第8章介绍了 LoopBack 开源框架的使用。本书没有介绍 Express（可能读者早已熟悉），因为本书希望为读者引荐一个更加强大易用的企业级 Web 框架。第9章则从 C 的角度介绍了Node 扩展模块的编写，这部分适合那些想要了解 V8 引擎的读者。可以说 C 是 Node 技术栈的基石。本书希望向读者呈现构成 Node 技术栈的JavaScript和C 全貌。
本书不假定读者有 Node 研发经验，但需熟悉 JavaScript。如果读者最近才接触编程，建议选一本更初级的教程，或者先到 W3School（http://www.w3school.com.cn/js/index.asp）上看看。本书每一章都有源码示例，这些示例大部分可以在 Node 支持的任何系统上运行，但也有例外。建议使用本书第3章介绍的容器，在 Linux 环境下运行本书示例。大部分示例代码可以从 https://github.com/classfellow/node-AdProgramming 下载。

饮半盏湖水，当知江河滋味；拾一片落叶，尽享人间秋凉。希望本书成为读者熟练掌握 Node 技术栈的那一盏湖水、一片落叶。

致谢
感谢 CNode 社区，它提供了一个非常好的平台，本书前期的一些章节从中得到了积极的反馈，使笔者有了继续写下去的动力。首都师范大学的刘晓莲同学，利用周末时间审阅了本书的稿件，提出的一些见解，使得本书在内容安排上更合理，更容易看懂，在此表示感谢。笔者周围的一些同事部分地阅读了初稿并给出了积极的反馈，在此一并谢过！
作者邮箱
classfellow@qq.com

尤嘉，东南大学计算机硕士，从事软件研发工作多年，先后就职于奇虎和猎豹移动。做过基于 chromium 的浏览器，也从事过 WebKit 与 V8 方面的研发工作。目前从事 P2P 与区块链方面的项目研发。

目 录

第1章 Node异步编程范式 ·····························································1

1.1 同步与异步的比较 ········································································2

1.2 Node异步的实现 ···········································································7

1.2.1 HTTP请求完全异步的例子 ·························································8

1.2.2 本地磁盘I/O多线程模拟 ··························································17

1.3 事件驱动 ··················································································18

参考资料 ····························································································19

第2章 搭建自己的开发环境 ·························································21

2.1 Node的编译与安装 ······································································22

2.2 开发与调试 ···············································································23

2.3 单元测试 ··················································································29

2.3.1 Mocha 测试框架 ··········································································29

2.3.2 TDD 风格 ··················································································32

2.3.3 BDD 风格 ··················································································34

2.3.4 生成不同形式的测试报告 ······························································35

2.3.5 代码覆盖率工具Istanbul·································································36

参考资料 ····························································································40

第3章 使用Docker部署Node服务 ··················································43

3.1 Docker基础 ···············································································44

3.2 在Docker中运行Node ··································································· 45

3.3 导出配置好的容器 ······································································ 47

参考资料 ···························································································· 48

第4章 Node模块 ······································································· 49

4.1 程序入口 ·················································································· 50

4.2 VM模块 ··················································································· 50

4.3 模块加载与缓存 ········································································· 52

4.4 模块分类 ·················································································· 54

4.5 正确导出模块 ············································································ 55

4.6 小心使用全局变量 ······································································ 56

第5章 V8引擎 ·········································································· 57

5.1 Java Script代码的编译与优化 ························································· 58

5.1.1 即时编译 ··················································································· 58

5.1.2 隐藏类 ······················································································ 59

5.1.3 内联缓存 ··················································································· 60

5.1.4 优化回退 ··················································································· 61

5.1.5 写出更具亲和性的代码 ································································· 62

5.1.6 借助TypeScript ············································································ 63

5.2 垃圾回收与内存控制 ··································································· 65

5.2.1 V8的垃圾回收算法 ······································································· 65

5.2.2 使用Buffer ················································································· 67

5.2.3 避免内存泄漏 ············································································· 70

参考资料 ···························································································· 77

V

第6章 Promise对象 ···································································· 79

6.1 Promise的含义 ··········································································· 80

6.2 基本用法 ·················································································· 80

6.3 then的链式写法 ·········································································· 82

6.4 bluebird库 ················································································· 85

参考资料 ···························································································· 86

第7章 用ES6 Generator解决回调金字塔 ········································· 87

7.1 Node异步实现流程 ······································································ 88

7.2 用Generator实现异步调用与多并发 ················································· 89

7.3 严格模式下运行 ········································································· 99

7.4 理解执行过程 ···········································································100

7.5 本章结语 ·················································································106

第8章 LoopBack开源框架 ··························································107

8.1 安装与运行 ··············································································108

8.2 路由与权限控制 ········································································113

8.3 添加新模型 ··············································································121

8.4 初始化数据库 ···········································································131

8.5 钩子机制 ·················································································134

8.6 中间件 ····················································································137

8.7 模型关系 ·················································································139

8.8 使用cluster模式运行服务 ·····························································141

参考资料 ··························································································· 144

第9章 编写C 扩展 ·································································145

9.1 使用C 编写扩展模块 ································································146

9.1.1 导出对象 ·················································································· 146

9.1.2 导出函数 ·················································································· 149

9.1.3 导出构造函数 ············································································ 151

9.2 线程模型与CPU密集型任务 ·························································164

9.3 线程对象 ·················································································164

9.4 本章结语 ·················································································170

参考资料 ··························································································· 170

附 录 ·····················································································171

附录 A JavaScript 严格模式 ·······························································172

附录 B JavaScript 编码规范 ······························································182

参考资料 ··························································································· 195