JavaScript: A Little Knowledge
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Summary
JavaScript: A Little Knowledge is a technical e-book compiled by a front-end developer who goes by the online handle dennis while learning JavaScript. The author gathered seventeen study notes scattered across his personal blog and reorganized them into a book. The motivation was simple: blog posts are scattered and inconvenient to search through; collecting them into a book makes it easier for the author to revisit later, easier to keep adding to, and lets fellow learners read everything in one go. The book does not aim for academic exhaustiveness or rigor; instead it targets "good enough, easy to understand, handy for reference" and covers the main modules from language fundamentals to browser-side development. It opens with syntax, data types, operators, expressions, statements, objects, arrays, and functions to lay a solid foundation; then moves to reference types, including Object, Array, Date, RegExp, primitive wrapper types, and singleton built-in objects such as Global, Math, and console; next it covers DOM and attributes, CSS manipulation, BOM, events, and regular expressions, extending to JSON, AJAX, forms and rich text editors, canvas, offline applications, and client-side storage (Cookie, Storage, IndexedDB); after that it introduces a set of HTML5 APIs, such as video/audio, geolocation, requestAnimationFrame, File API, fullscreen, Blob, WebRTC, Page Visibility, and Performance; the final section returns to the language itself, discussing object-oriented programming, the this keyword, the prototype chain, scope, a collection of common APIs, SVG, error handling mechanisms, development tips and coding style, and garbage collection. In the preface the author candidly admits he is no "guru" and that the book inevitably contains omissions and inaccuracies, and welcomes readers' corrections. This candor also defines the book's positioning: it is more a clearly structured, moderately dense set of study notes and a quick-reference manual than a textbook meant to replace authoritative guides.
Editor's review
先把一件事说清楚：这不是出版社的正式出版物，而是一位网名 dennis 的开发者在看云平台上发布的个人技术电子书，最初只是他博客上的十七篇 JavaScript 学习笔记，整理成册后在网上流传颇广，常被前端学习者列入“入门书单”当作补充读物。也正因如此，它没有 ISBN、没有印张，也没有豆瓣评分，你几乎不可能在实体书店买到它。它的价值不在权威，而在思路：作者把 JavaScript 的知识点按“语言基础—引用类型—DOM/BOM—事件与正则—异步与请求—HTML5 API—面向对象与底层机制”这条线串起来，形成一张相对完整的知识地图，读者可以顺着读，也可以按目录挑着查。书中用了大量短小的实例来讲知识点，符合作者一贯“以实例说话”的写作风格，对刚接触前端、被零散教程绕晕的人来说，这种结构清晰的笔记体反而比厚重大部头更容易推进。需要提醒的是，书中的内容基于当年的技术生态，ES5 时代的语法和 API 占主导，部分浏览器特性、离线应用与 canvas 相关章节已显陈旧，阅读时应与现代标准和 MDN 对照；作者本人也在前言里坦承水平有限、难免谬误。把它定位成“一位认真同行的学习地图与速查手册”，你会用得最舒服。
Who it's for
A good fit for
- 已有一点 JavaScript 基础、想系统梳理知识框架的初学者
- 喜欢按目录挑章节查、偏好实例讲解的读者
- 需要一份结构清晰的速查笔记、随手翻阅的前端从业者
- 预算有限、习惯免费或低成本在线技术文档的学习者
Not a good fit for
- 希望获得权威、经严格审校的教材级内容的读者
- 零基础、尚无任何编程概念、需要手把手入门的人
- 以 ES6+ 与现代前端工程化为主要学习目标的读者
Reading tips
- 建议先读前言与“基本概念”部分，确认自己的基础是否能跟上后续章节。
- 把它当作地图而非终点：遇到难点再对照《JavaScript 高级程序设计》或 MDN 深入。
- 阅读 HTML5 API 章节时注意核对现代浏览器兼容性，不照搬书中的旧写法。
- 可按“基础→DOM/BOM→面向对象与原型”顺序阅读，其余章节按需跳读。
Contents
- Preface
- Introduction to JavaScript
- Basic Concepts: Syntax
- Basic Concepts: Data Types
- Basic Concepts: Operators
- Basic Concepts: Expressions
- Basic Concepts: Statements
- Basic Concepts: Objects
- Basic Concepts: Arrays
- Basic Concepts: Functions
- Reference Types (Objects): The Object Object
- Reference Types (Objects): The Array Object
- Reference Types (Objects): The Date Object
- Reference Types (Objects): The RegExp Object
- Reference Types (Objects): Primitive Wrapper Types (Boolean, Number, String)
- Reference Types (Objects): Singleton Built-in Objects (Global, Math)
- Reference Types (Objects): The console Object
- DOM
- DOM: Attributes and CSS
- BOM
- Event Events
- Regular Expressions
- JSON
- AJAX
- Forms and Rich Text Editors: Forms
- Forms and Rich Text Editors: Rich Text Editors
- canvas
- Offline Applications
- Client-side Storage (Cookie, Storage, IndexedDB)
- HTML5 API: Video/Audio
- HTML5 API: Geolocation API
- HTML5 API: requestAnimationFrame
- HTML5 API: File API
- HTML5 API: FullScreen API
- HTML5 API: IndexedDB
- HTML5 API: Detecting Device Orientation
- HTML5 API: Blob
- HTML5 API: vibrate
- HTML5 API: Luminosity API
- HTML5 API: WebRTC
FAQ
这本书是正式出版物吗？能买到纸质版吗？
不是。它是作者 dennis 在看云平台发布的个人技术电子书，由博客上十七篇 JavaScript 学习笔记整理而成，没有出版社与 ISBN，一般只能在线获取电子版，无法在书店买到纸质书。
在哪里可以读到这本书？
作者发布在看云平台，书名为《JavaScript半知半解》。由于内容会更新，具体地址建议直接在看云搜索作者 dennis 或书名获取；作者在前言中也说明未经许可请勿将此书电子版上传到其他网站。
零基础可以直接读这本书吗？
不太建议。书中虽从语法、数据类型等基础讲起，但节奏偏笔记体，缺少循序渐进的练习设计。零基础读者先用一本成体系的入门书打底，再回头用它梳理框架会更高效。
书里的内容现在过时了吗？
部分已过时。书中内容以 ES5 时代的语法与浏览器 API 为主，HTML5 离线应用、canvas、部分 API 章节与今天的标准有差距。语言基础部分仍有参考价值，实践时应对照 MDN 等现代文档。
书名叫“半知半解”是什么意思？
取自“一知半解”，是作者的自谦说法：书中的内容是作者学习所得，水平有限、难免有错误和不准确之处，也提示读者以半懂到真懂为目标继续深入，而不是停在会用的层面。
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