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Airbnb JavaScript Style Guide() {

用更合理的方式写 JavaScript

译注：
本篇为 ES2015/ES6 版 Airbnb JavaScript 风格规范。你可能需要搭配 Babel 来使用。
我也翻译了 Airbnb JavaScript 风格规范的 ES5 版，适用于国内常见 Web 前端开发环境。

目录

  1. 类型
  2. 引用
  3. 对象
  4. 数组
  5. 解构
  6. 字符串
  7. 函数
  8. 箭头函数
  9. 类与构造函数
  10. 模块
  11. 迭代器和生成器
  12. 属性
  13. 变量
  14. Hoisting
  15. Comparison Operators & Equality
  16. Blocks
  17. Comments
  18. Whitespace
  19. Commas
  20. Semicolons
  21. Type Casting & Coercion
  22. Naming Conventions
  23. Accessors
  24. Events
  25. jQuery
  26. ECMAScript 5 Compatibility
  27. ECMAScript 6 Styles
  28. Testing
  29. Performance
  30. Resources
  31. In the Wild
  32. Translation
  33. The JavaScript Style Guide Guide
  34. Chat With Us About JavaScript
  35. Contributors
  36. License

类型

  • 1.1 原始值：存取直接作用于它自身。

    • string
    • number
    • boolean
    • null
    • undefined
    const foo = 1;
let bar = foo;

bar = 9;

console.log(foo, bar); // => 1, 9

  • 1.2 复杂类型：存取时作用于它自身值的引用。

    • object
    • array
    • function
    const foo = [1, 2];
const bar = foo;

bar[0] = 9;

console.log(foo[0], bar[0]); // => 9, 9

⬆ 回到顶部

引用

  • 2.1 使用 const 进行引用，避免使用 var。eslint: prefer-const, no-const-assign

    为什么？这将确保你不能对引用重新赋值，从而不会导致出错或让代码难以理解。

    // bad
var a = 1;
var b = 2;

// good
const a = 1;
const b = 2;

  • 2.2 如果你必须对引用重新赋值，使用 let 代替 var。eslint: no-var jscs: disallowVar

    为什么？相较于函数作用域的 var，let 的作用域在区块内。

    // bad
var count = 1;
if (true) {
  count += 1;
}

// good, use the let.
let count = 1;
if (true) {
  count += 1;
}

  • 2.3 要注意 let 和 const 都是块级作用域。

    // const 和 let 只存在于它们被定义的区块内。
{
  let a = 1;
  const b = 1;
}
console.log(a); // ReferenceError
console.log(b); // ReferenceError

⬆ 回到顶部

对象

  • 3.1 使用直接量创建对象。eslint: no-new-object

    // bad
const item = new Object();

// good
const item = {};

  • 3.2 如果你的代码将要在浏览器中执行，不要使用保留字作为键名。它们在 IE8 下不会工作。更多信息。但可以在 ES6 模块中或者服务器端代码使用它们。jscs: disallowIdentifierNames

    // bad
const superman = {
  default: { clark: 'kent' },
  private: true,
};

// good
const superman = {
  defaults: { clark: 'kent' },
  hidden: true,
};

  • 3.3 使用可读性强的同义词替换需要使用的保留字。jscs: disallowIdentifierNames

    // bad
const superman = {
  class: 'alien',
};

// bad
const superman = {
  klass: 'alien',
};

// good
const superman = {
  type: 'alien',
};

  • 3.4 创建含有动态属性名的对象时，使用可被计算的属性名。

    为什么？这样你可以在一个地方定义一个对象的所有属性。

    function getKey(k) {
  return `a key named ${k}`;
}

// bad
const obj = {
  id: 5,
  name: 'San Francisco',
};
obj[getKey('enabled')] = true;

// good
const obj = {
  id: 5,
  name: 'San Francisco',
  [getKey('enabled')]: true,
};

  • 3.5 使用对象方法的简写方式。eslint: object-shorthand jscs: requireEnhancedObjectLiterals

    // bad
const atom = {
  value: 1,

  addValue: function (value) {
    return atom.value + value;
  },
};

// good
const atom = {
  value: 1,

  addValue(value) {
    return atom.value + value;
  },
};

  • 3.6 使用属性值的简写方式。eslint: object-shorthand jscs: requireEnhancedObjectLiterals

    为什么？这样写起来更短且更有描述性。

    const lukeSkywalker = 'Luke Skywalker';

// bad
const obj = {
  lukeSkywalker: lukeSkywalker,
};

// good
const obj = {
  lukeSkywalker,
};

  • 3.7 把简写的属性值归类放在对象声明的开头。

    为什么？这样更容易表述哪些属性值在使用简写方式。

    const anakinSkywalker = 'Anakin Skywalker';
const lukeSkywalker = 'Luke Skywalker';

// bad
const obj = {
  episodeOne: 1,
  twoJediWalkIntoACantina: 2,
  lukeSkywalker,
  episodeThree: 3,
  mayTheFourth: 4,
  anakinSkywalker,
};

// good
const obj = {
  lukeSkywalker,
  anakinSkywalker,
  episodeOne: 1,
  twoJediWalkIntoACantina: 2,
  episodeThree: 3,
  mayTheFourth: 4,
};

为什么？通常我们认为这样写主观上更容易阅读。这样做改善了语法高亮并且更容易被多数 JS 引擎优化。

// bad
const bad = {
  'foo': 3,
  'bar': 4,
  'data-blah': 5,
};

// good
const good = {
  foo: 3,
  bar: 4,
  'data-blah': 5,
};

  • 3.9 不要直接调用 Object.prototype 里的方法，比如 hasOwnProperty、propertyIsEnumerable 以及 isPrototypeOf。

为什么？这些方法可能会被有问题的对象属性所遮蔽。考虑 { hasOwnProperty: false }，或者对象本身是一个空对象（Object.create(null)）。

// bad
console.log(object.hasOwnProperty(key));

// good
console.log(Object.prototype.hasOwnProperty.call(object, key));

// best
const has = Object.prototype.hasOwnProperty; // 在模块作用域缓存查找结果
/* or */
const has = require('has');
…
console.log(has.call(object, key));

⬆ 回到顶部

数组

  • 4.1 使用直接量创建数组。eslint: no-array-constructor

    // bad
const items = new Array();

// good
const items = [];

  • 4.2 向数组增加元素时使用 Array#push 替代直接赋值。

    const someStack = [];

// bad
someStack[someStack.length] = 'abracadabra';

// good
someStack.push('abracadabra');

  • 4.3 使用数组展开 ... 来拷贝数组。

    // bad
const len = items.length;
const itemsCopy = [];
let i;

for (i = 0; i < len; i++) {
  itemsCopy[i] = items[i];
}

// good
const itemsCopy = [...items];

  • 4.4 使用 Array.from 将类数组对象转换成数组。

    const foo = document.querySelectorAll('.foo');
const nodes = Array.from(foo);

  • 4.5 在数组方法回调中使用返回语句。如果函数体遵守 8.2 的写法只包含一段语句则可以省略返回。eslint: array-callback-return

    // good
[1, 2, 3].map((x) => {
  const y = x + 1;
  return x * y;
});

// good
[1, 2, 3].map(x => x + 1);

// bad
const flat = {};
[[0, 1], [2, 3], [4, 5]].reduce((memo, item, index) => {
  const flatten = memo.concat(item);
  flat[index] = flatten;
});

// good
const flat = {};
[[0, 1], [2, 3], [4, 5]].reduce((memo, item, index) => {
  const flatten = memo.concat(item);
  flat[index] = flatten;
  return flatten;
});

// bad
inbox.filter((msg) => {
  const { subject, author } = msg;
  if (subject === 'Mockingbird') {
    return author === 'Harper Lee';
  } else {
    return false;
  }
});

// good
inbox.filter((msg) => {
  const { subject, author } = msg;
  if (subject === 'Mockingbird') {
    return author === 'Harper Lee';
  }

  return false;
});

⬆ 回到顶部

解构

  • 5.1 在访问和使用一个对象的多个属性时使用对象解构。jscs: requireObjectDestructuring

    为什么？解构可以让你免于创建这些属性的临时引用。

    // bad
function getFullName(user) {
  const firstName = user.firstName;
  const lastName = user.lastName;

  return `${firstName} ${lastName}`;
}

// good
function getFullName(user) {
  const { firstName, lastName } = user;
  return `${firstName} ${lastName}`;
}

// best
function getFullName({ firstName, lastName }) {
  return `${firstName} ${lastName}`;
}

  • 5.2 使用数组解构。jscs: requireArrayDestructuring

    const arr = [1, 2, 3, 4];

// bad
const first = arr[0];
const second = arr[1];

// good
const [first, second] = arr;

  • 5.3 处理多个返回值时使用对象解构而不是数组解构。jscs: disallowArrayDestructuringReturn

    为什么？你可以随着时间的推移不断向里增加新属性或在不破坏调用位置的前提下改变次序。

    // bad
function processInput(input) {
  // then a miracle occurs
  return [left, right, top, bottom];
}

// 调用时需要考虑返回数据的顺序
const [left, __, top] = processInput(input);

// good
function processInput(input) {
  // then a miracle occurs
  return { left, right, top, bottom };
}

// 只选择需要的数据调用
const { left, top } = processInput(input);

⬆ 回到顶部

字符串

  • 6.1 使用单引号 '' 包裹字符串。eslint: quotes jscs: validateQuoteMarks

    // bad
const name = "Capt. Janeway";

// good
const name = 'Capt. Janeway';

  • 6.2 超过 100 个字符的字符串应该使用连接符写成多行。

  • 6.3 注：若过度使用，通过连接符连接的长字符串会影响性能。jsPerf & Discussion.

    // bad
const errorMessage = 'This is a super long error that was thrown because of Batman. When you stop to think about how Batman had anything to do with this, you would get nowhere fast.';

// bad
const errorMessage = 'This is a super long error that was thrown because \
of Batman. When you stop to think about how Batman had anything to do \
with this, you would get nowhere \
fast.';

// good
const errorMessage = 'This is a super long error that was thrown because ' +
  'of Batman. When you stop to think about how Batman had anything to do ' +
  'with this, you would get nowhere fast.';

  • 6.4 程序化生成的字符串时使用模板字符串替代串联。eslint: prefer-template template-curly-spacing jscs: requireTemplateStrings

    为什么？模板字符串提供了可读并简洁的语法以及正确的换行符和字符串插值特性。

    // bad
function sayHi(name) {
  return 'How are you, ' + name + '?';
}

// bad
function sayHi(name) {
  return ['How are you, ', name, '?'].join();
}

// bad
function sayHi(name) {
  return `How are you, ${ name }?`;
}

// good
function sayHi(name) {
  return `How are you, ${name}?`;
}

  • 6.5 永远不要在字符串上使用 eval()，它开启了太多漏洞。

  • 6.6 不要在字符串中没理由的使用转义符。eslint: no-useless-escape

    为什么？反斜线破坏可读性，所以它们只应当在必要时存在。

    // bad
const foo = '\'this\' \i\s \"quoted\"';

// good
const foo = '\'this\' is "quoted"';
const foo = `'this' is "quoted"`;

⬆ 回到顶部

函数

  • 7.1 使用函数声明替代函数表达式。jscs: requireFunctionDeclarations

    为什么？函数声明是被命名的，所以他们在调用栈中更容易被识别。此外，函数声明体自身会被提升（hoisted），而函数表达式只有它的引用会被提升。这条规则使得总是使用箭头函数替代函数表达式成为可能。

    // bad
const foo = function () {
};

// good
function foo() {
}

  • 7.2 使用圆括号包括立即调用函数表达式。eslint: wrap-iife jscs: requireParenthesesAroundIIFE

    为什么？一个立即调用函数表达式是一个独立单元 —— 用圆括号将它自身和调用括号包裹在一起来明确表达这一点。注意在一个模块的世界，你几乎永远都不需要立即调用函数。

    // 立即调用函数表达式（IIFE）
(function () {
  console.log('Welcome to the Internet. Please follow me.');
}());

  • 7.3 永远不要在非函数代码块（if、while 等）中声明一个函数。通过把函数赋值给一个变量来替代它。虽然浏览器允许这么做，但它们的解析表现不一致。eslint: no-loop-func

  • 7.4 注： ECMA-262 把 块 定义为一组语句。函数声明不是语句。阅读对 ECMA-262 这个问题的说明。

    // bad
if (currentUser) {
  function test() {
    console.log('Nope.');
  }
}

// good
let test;
if (currentUser) {
  test = () => {
    console.log('Yup.');
  };
}

  • 7.5 永远不要把参数命名为 arguments。这将取代函数作用域内的 arguments 对象。

    // bad
function nope(name, options, arguments) {
  // ...stuff...
}

// good
function yup(name, options, args) {
  // ...stuff...
}

  • 7.6 永远不要使用 arguments，使用剩余参数语法 ... 来替代。eslint: prefer-rest-params

    为什么？... 明确说明了你想传入的参数。此外，剩余参数是真正的数组，而不像 arguments 仅仅是类数组。

    // bad
function concatenateAll() {
  const args = Array.prototype.slice.call(arguments);
  return args.join('');
}

// good
function concatenateAll(...args) {
  return args.join('');
}

  • 7.7 使用默认参数值语法而不是转变函数参数。

    // really bad
function handleThings(opts) {
  // 错！我们不应该变动函数参数。
  // 再错：如果参数 opts 为否值，它将被设为一个你想要对象，但这将带来隐性 bug。
  opts = opts || {};
  // ...
}

// still bad
function handleThings(opts) {
  if (opts === void 0) {
    opts = {};
  }
  // ...
}

// good
function handleThings(opts = {}) {
  // ...
}

  • 7.8 避免采用默认参数时的副作用。

    为什么？它们难以理解。

    var b = 1;
// bad
function count(a = b++) {
  console.log(a);
}
count();  // 1
count();  // 2
count(3); // 3
count();  // 3

  • 7.9 总是把默认参数放到最后。

    // bad
function handleThings(opts = {}, name) {
  // ...
}

// good
function handleThings(name, opts = {}) {
  // ...
}

  • 7.10 永远不要使用函数构造器创建新函数。

    为什么？通过这种方式创建的函数在处理字符串时会像 eval() 一样开启漏洞。

    // bad
var add = new Function('a', 'b', 'return a + b');

// still bad
var subtract = Function('a', 'b', 'return a - b');

  • 7.11 在函数标识中添加空格。

    为什么？保持一致性是好的，而且你不需要在增加或删除函数名是增减空格。

    // bad
const f = function(){};
const g = function (){};
const h = function() {};

// good
const x = function () {};
const y = function a() {};

  • 7.12 永远不要转变参数。eslint: no-param-reassign

    为什么？操作以参数传入的对象会在原始调用处引起不期望的副作用。

    // bad
function f1(obj) {
  obj.key = 1;
};

// good
function f2(obj) {
  const key = Object.prototype.hasOwnProperty.call(obj, 'key') ? obj.key : 1;
};

  • 7.13 永远不要给参数重新赋值。eslint: no-param-reassign

    为什么？给参数重新赋值会导致预料外的行为，尤其是访问 arguments 对象时。同时这会引起优化问题，尤其在 V8 下。

    // bad
function f1(a) {
  a = 1;
}

function f2(a) {
  if (!a) { a = 1; }
}

// good
function f3(a) {
  const b = a || 1;
}

function f4(a = 1) {
}

⬆ 回到顶部

箭头函数

  • 8.1 当你必须使用函数表达式时（比如传入匿名函数的时候），使用箭头函数符号。eslint: prefer-arrow-callback, arrow-spacing jscs: requireArrowFunctions

    为什么？它建立了的函数以上下文的 this 作为自己的 this 值，这往往是你想要的，并且它的语法更简洁。

    为什么不？如果你有一个相当复杂的函数，你或许应该把逻辑移出到它自己的函数声明中。

    // bad
[1, 2, 3].map(function (x) {
  const y = x + 1;
  return x * y;
});

// good
[1, 2, 3].map((x) => {
  const y = x + 1;
  return x * y;
});

  • 8.2 如果函数体只由一句表达式构成，移除花括号并且使用其内置的返回。除此之外的情况，使用花括号并使用 return 语句。eslint: arrow-parens, arrow-body-style jscs: disallowParenthesesAroundArrowParam, requireShorthandArrowFunctions

    为什么？语法糖。当多个函数串联在一起时可读性更好。

    // bad
[1, 2, 3].map(number => {
  const nextNumber = number + 1;
  `A string containing the ${nextNumber}.`;
});

// good
[1, 2, 3].map(number => `A string containing the ${number}.`);

// good
[1, 2, 3].map((number) => {
  const nextNumber = number + 1;
  return `A string containing the ${nextNumber}.`;
});

// good
[1, 2, 3].map((number, index) => ({
  index: number
}));

  • 8.3 在表达式跨越多行的情况下，使用圆括号包裹获得NG更好的可读性。

    为什么？这样能更清晰的表达函数的开始与结束。

    // bad
[1, 2, 3].map(number => 'As time went by, the string containing the ' +
  `${number} became much longer. So we needed to break it over multiple ` +
  'lines.'
);

// good
[1, 2, 3].map(number => (
  `As time went by, the string containing the ${number} became much ` +
  'longer. So we needed to break it over multiple lines.'
));

  • 8.4 如果函数只传入一个参数并且不需要花括号，删掉圆括号。除此之外的情况，总是使用圆括号包裹参数。eslint: arrow-parens jscs: disallowParenthesesAroundArrowParam

    为什么？减少视觉干扰。

    // bad
[1, 2, 3].map((x) => x * x);

// good
[1, 2, 3].map(x => x * x);

// good
[1, 2, 3].map(number => (
  `A long string with the ${number}. It’s so long that we’ve broken it ` +
  'over multiple lines!'
));

// bad
[1, 2, 3].map(x => {
  const y = x + 1;
  return x * y;
});

// good
[1, 2, 3].map((x) => {
  const y = x + 1;
  return x * y;
});

  • 8.5 避免混淆箭头函数语法（=>）和比较操作符（<=、>=）。eslint: no-confusing-arrow

    // bad
const itemHeight = item => item.height > 256 ? item.largeSize : item.smallSize;

// bad
const itemHeight = (item) => item.height > 256 ? item.largeSize : item.smallSize;

// good
const itemHeight = item => (item.height > 256 ? item.largeSize : item.smallSize);

// good
const itemHeight = (item) => {
  const { height, largeSize, smallSize } = item;
  return height > 256 ? largeSize : smallSize;
};

⬆ 回到顶部

类与构造函数

  • 9.1 总是使用 class。避免直接操作 prototype。

    为什么？使用 class 语法更简洁易读。

    // bad
function Queue(contents = []) {
  this.queue = [...contents];
}
Queue.prototype.pop = function () {
  const value = this.queue[0];
  this.queue.splice(0, 1);
  return value;
};


// good
class Queue {
  constructor(contents = []) {
    this.queue = [...contents];
  }
  pop() {
    const value = this.queue[0];
    this.queue.splice(0, 1);
    return value;
  }
}

  • 9.2 使用 extends 来继承。

    为什么？这是内置的继承原型方法的方式，而且不会破坏 instanceof。

    // bad
const inherits = require('inherits');
function PeekableQueue(contents) {
  Queue.apply(this, contents);
}
inherits(PeekableQueue, Queue);
PeekableQueue.prototype.peek = function () {
  return this._queue[0];
}

// good
class PeekableQueue extends Queue {
  peek() {
    return this._queue[0];
  }
}

  • 9.3 方法能返回 this 可以帮助实现方法链接。

    // bad
Jedi.prototype.jump = function () {
  this.jumping = true;
  return true;
};

Jedi.prototype.setHeight = function (height) {
  this.height = height;
};

const luke = new Jedi();
luke.jump(); // => true
luke.setHeight(20); // => undefined

// good
class Jedi {
  jump() {
    this.jumping = true;
    return this;
  }

  setHeight(height) {
    this.height = height;
    return this;
  }
}

const luke = new Jedi();

luke.jump()
  .setHeight(20);

  • 9.4 自己写一个 toString() 方法是可以的，只要能确保它可以正常工作并且没有副作用就行。

    class Jedi {
  constructor(options = {}) {
    this.name = options.name || 'no name';
  }

  getName() {
    return this.name;
  }

  toString() {
    return `Jedi - ${this.getName()}`;
  }
}

  • 9.5 类在没有特别指定的情况下会有一个默认的构造函数。没有必要使用一个空的构造函数或者委托给父级类。eslint: no-useless-constructor

    // bad
class Jedi {
  constructor() {}

  getName() {
    return this.name;
  }
}

// bad
class Rey extends Jedi {
  constructor(...args) {
    super(...args);
  }
}

// good
class Rey extends Jedi {
  constructor(...args) {
    super(...args);
    this.name = 'Rey';
  }
}

  • 9.6 避免拷贝类成员。eslint: no-dupe-class-members

    为什么？拷贝类成员声明将默认采用最后一个——拥有多个拷贝毫无疑问算得上是一个 bug。

    // bad
class Foo {
  bar() { return 1; }
  bar() { return 2; }
}

// good
class Foo {
  bar() { return 1; }
}

// good
class Foo {
  bar() { return 2; }
}

⬆ 回到顶部

模块

  • 10.1 总是使用 ES6 模块（import/export）优先于非标准的模块系统。你可以编译到你喜欢的模块系统。

    为什么？ES6 模块是未来，让我现在就开始使用它。

    // bad
const AirbnbStyleGuide = require('./AirbnbStyleGuide');
module.exports = AirbnbStyleGuide.es6;

// ok
import AirbnbStyleGuide from './AirbnbStyleGuide';
export default AirbnbStyleGuide.es6;

// best
import { es6 } from './AirbnbStyleGuide';
export default es6;

  • 10.2 不要使用通配符导入。

    为什么？这样确保你有一个默认的输出。

    // bad
import * as AirbnbStyleGuide from './AirbnbStyleGuide';

// good
import AirbnbStyleGuide from './AirbnbStyleGuide';

  • 10.3 不要从导入模块的地方直接导出。

    为什么？尽管单行写法很简洁，但是用明确的方式导入和导出模块更能保持一致性。

    // bad
// filename es6.js
export { es6 as default } from './airbnbStyleGuide';

// good
// filename es6.js
import { es6 } from './AirbnbStyleGuide';
export default es6;

  • 10.4 在同一个位置引用模块时只导入一次。eslint: no-duplicate-imports

    为什么？使用多行导入同一个位置的模块会让代码难以维护。

    // bad
import foo from 'foo';
// … some other imports … //
import { named1, named2 } from 'foo';

// good
import foo, { named1, named2 } from 'foo';

// good
import foo, {
  named1,
  named2,
} from 'foo';

  • 10.5 不要导出可变的变量绑定。eslint: import/no-mutable-exports

    为什么？可变的导出通常应该避免，除非有意要导出可变的变量绑定。虽然这种方法可能在某些特殊情况下需要，但通常还是要确保只导出常量引用。（这段翻译的不好：Why? Mutation should be avoided in general, but in particular when exporting mutable bindings. While this technique may be needed for some special cases, in general, only constant references should be exported.）

    // bad
let foo = 3;
export { foo }

// good
const foo = 3;
export { foo }

  • 10.6 只包含一个导出的模块，应优先使用默认导出而不是命名导出。 eslint: import/prefer-default-export

    // bad
export function foo() {}

// good
export default function foo() {}

  • 10.7 把所有 import 放到非导入语句上面。eslint: import/imports-first

    为什么？由于 import 会被声明提升，所以保持它们在顶部以防止意外行为发生。

    // bad
import foo from 'foo';
foo.init();

import bar from 'bar';

// good
import foo from 'foo';
import bar from 'bar';

foo.init();

⬆ 回到顶部

迭代器和生成器

  • 11.1 不要使用迭代器。优先使用 JavaScript 的高阶函数，例如使用 map() 和 reduce() 来替代 for-of 循环。eslint: no-iterator

    为什么？这样强化了我们不可改变的规则。比起副作用，处理带返回值的纯函数更容易理解。

    const numbers = [1, 2, 3, 4, 5];

// bad
let sum = 0;
for (let num of numbers) {
  sum += num;
}

sum === 15;

// good
let sum = 0;
numbers.forEach(num => sum += num);
sum === 15;

// best (use the functional force)
const sum = numbers.reduce((total, num) => total + num, 0);
sum === 15;

  • 11.2 现在先不要使用生成器。

    为什么？他们还不能很好的编译到 ES5。

  • 11.3 如果你必须使用生成器，或者你不在乎我们的建议，确保他们的函数声明里正确的使用了空格。eslint: generator-star-spacing

    为什么？function 和 * 是同一概念的关键词的一部分—— * 不是 function 的修饰符号，function* 是一种独立的结构，与 function 不同。

    // bad
function * foo() {
}

const bar = function * () {
}

const baz = function *() {
}

const quux = function*() {
}

function*foo() {
}

function *foo() {
}

// very bad
function
*
foo() {
}

const wat = function
*
() {
}

// good
function* foo() {
}

const foo = function* () {
}

⬆ 回到顶部

属性

  • 12.1 使用点标记来访问对象的属性。eslint: dot-notation jscs: requireDotNotation

    const luke = {
  jedi: true,
  age: 28,
};

// bad
const isJedi = luke['jedi'];

// good
const isJedi = luke.jedi;

  • 12.2 使用中括号标记 [] 访问带变量的属性。

    const luke = {
  jedi: true,
  age: 28,
};

function getProp(prop) {
  return luke[prop];
}

const isJedi = getProp('jedi');

⬆ 回到顶部

变量

  • 13.1 总是使用 const 声明变量。不这么做将导致产生全局变量。我们要避免污染全局命名空间。地球队长警告过我们这个。

    // bad
superPower = new SuperPower();

// good
const superPower = new SuperPower();

  • 13.2 使用 const 声明每一个变量。eslint: one-var jscs: disallowMultipleVarDecl

    为什么？这样做更容易增加新变量，而且你永远不用再担心调换错 ; 跟 , 或者引入标点符号差异。你也能够逐行调试每个声明而不是每次全改一遍。

    // bad
const items = getItems(),
    goSportsTeam = true,
    dragonball = 'z';

// bad
// (compare to above, and try to spot the mistake)
const items = getItems(),
    goSportsTeam = true;
    dragonball = 'z';

// good
const items = getItems();
const goSportsTeam = true;
const dragonball = 'z';

  • 13.3 按照先 const 后 let 的方式对所有声明进行分组。

    为什么？当你需要引用前面的变量赋值时这将变的很有用。

    // bad
let i, len, dragonball,
    items = getItems(),
    goSportsTeam = true;

// bad
let i;
const items = getItems();
let dragonball;
const goSportsTeam = true;
let len;

// good
const goSportsTeam = true;
const items = getItems();
let dragonball;
let i;
let length;

  • 13.4 在使用变量的地方进行赋值，但要把它们放到合理的位置。

    为什么？let 和 const 是块级作用域而不是函数作用域。

    // bad - unnecessary function call
function checkName(hasName) {
  const name = getName();

  if (hasName === 'test') {
    return false;
  }

  if (name === 'test') {
    this.setName('');
    return false;
  }

  return name;
}

// good
function checkName(hasName) {
  if (hasName === 'test') {
    return false;
  }

  const name = getName();

  if (name === 'test') {
    this.setName('');
    return false;
  }

  return name;
}

⬆ 回到顶部

Hoisting

  • 14.1 var declarations get hoisted to the top of their scope, their assignment does not. const and let declarations are blessed with a new concept called Temporal Dead Zones (TDZ). It's important to know why typeof is no longer safe.

    // we know this wouldn't work (assuming there
// is no notDefined global variable)
function example() {
  console.log(notDefined); // => throws a ReferenceError
}

// creating a variable declaration after you
// reference the variable will work due to
// variable hoisting. Note: the assignment
// value of `true` is not hoisted.
function example() {
  console.log(declaredButNotAssigned); // => undefined
  var declaredButNotAssigned = true;
}

// the interpreter is hoisting the variable
// declaration to the top of the scope,
// which means our example could be rewritten as:
function example() {
  let declaredButNotAssigned;
  console.log(declaredButNotAssigned); // => undefined
  declaredButNotAssigned = true;
}

// using const and let
function example() {
  console.log(declaredButNotAssigned); // => throws a ReferenceError
  console.log(typeof declaredButNotAssigned); // => throws a ReferenceError
  const declaredButNotAssigned = true;
}

  • 14.2 Anonymous function expressions hoist their variable name, but not the function assignment.

    function example() {
  console.log(anonymous); // => undefined

  anonymous(); // => TypeError anonymous is not a function

  var anonymous = function () {
    console.log('anonymous function expression');
  };
}

  • 14.3 Named function expressions hoist the variable name, not the function name or the function body.

    function example() {
  console.log(named); // => undefined

  named(); // => TypeError named is not a function

  superPower(); // => ReferenceError superPower is not defined

  var named = function superPower() {
    console.log('Flying');
  };
}

// the same is true when the function name
// is the same as the variable name.
function example() {
  console.log(named); // => undefined

  named(); // => TypeError named is not a function

  var named = function named() {
    console.log('named');
  }
}

  • 14.4 Function declarations hoist their name and the function body.

    function example() {
  superPower(); // => Flying

  function superPower() {
    console.log('Flying');
  }
}

  • For more information refer to JavaScript Scoping & Hoisting by Ben Cherry.

⬆ 回到顶部

Comparison Operators & Equality

  • 15.1 Use === and !== over == and !=. eslint: eqeqeq

  • 15.2 Conditional statements such as the if statement evaluate their expression using coercion with the ToBoolean abstract method and always follow these simple rules:

    • Objects evaluate to true
    • Undefined evaluates to false
    • Null evaluates to false
    • Booleans evaluate to the value of the boolean
    • Numbers evaluate to false if +0, -0, or NaN, otherwise true
    • Strings evaluate to false if an empty string '', otherwise true
    if ([0] && []) {
  // true
  // an array (even an empty one) is an object, objects will evaluate to true
}

  • 15.3 Use shortcuts.

    // bad
if (name !== '') {
  // ...stuff...
}

// good
if (name) {
  // ...stuff...
}

// bad
if (collection.length > 0) {
  // ...stuff...
}

// good
if (collection.length) {
  // ...stuff...
}

  • 15.5 Use braces to create blocks in case and default clauses that contain lexical declarations (e.g. let, const, function, and class).

Why? Lexical declarations are visible in the entire switch block but only get initialized when assigned, which only happens when its case is reached. This causes problems when multiple case clauses attempt to define the same thing.

eslint rules: no-case-declarations.

```javascript
// bad
switch (foo) {
  case 1:
    let x = 1;
    break;
  case 2:
    const y = 2;
    break;
  case 3:
    function f() {}
    break;
  default:
    class C {}
}

// good
switch (foo) {
  case 1: {
    let x = 1;
    break;
  }
  case 2: {
    const y = 2;
    break;
  }
  case 3: {
    function f() {}
    break;
  }
  case 4:
    bar();
    break;
  default: {
    class C {}
  }
}
```

  • 15.6 Ternaries should not be nested and generally be single line expressions.

    eslint rules: no-nested-ternary.

    // bad
const foo = maybe1 > maybe2
  ? "bar"
  : value1 > value2 ? "baz" : null;

// better
const maybeNull = value1 > value2 ? 'baz' : null;

const foo = maybe1 > maybe2
  ? 'bar'
  : maybeNull;

// best
const maybeNull = value1 > value2 ? 'baz' : null;

const foo = maybe1 > maybe2 ? 'bar' : maybeNull;

  • 15.7 Avoid unneeded ternary statements.

    eslint rules: no-unneeded-ternary.

    // bad
const foo = a ? a : b;
const bar = c ? true : false;
const baz = c ? false : true;

// good
const foo = a || b;
const bar = !!c;
const baz = !c;

⬆ 回到顶部

Blocks

  • 16.1 Use braces with all multi-line blocks.

    // bad
if (test)
  return false;

// good
if (test) return false;

// good
if (test) {
  return false;
}

// bad
function foo() { return false; }

// good
function bar() {
  return false;
}

  • 16.2 If you're using multi-line blocks with if and else, put else on the same line as your if block's closing brace. eslint: brace-style jscs: disallowNewlineBeforeBlockStatements

    // bad
if (test) {
  thing1();
  thing2();
}
else {
  thing3();
}

// good
if (test) {
  thing1();
  thing2();
} else {
  thing3();
}

⬆ 回到顶部

Comments

  • 17.1 Use /** ... */ for multi-line comments. Include a description, specify types and values for all parameters and return values.

    // bad
// make() returns a new element
// based on the passed in tag name
//
// @param {String} tag
// @return {Element} element
function make(tag) {

  // ...stuff...

  return element;
}

// good
/**
 * make() returns a new element
 * based on the passed in tag name
 *
 * @param {String} tag
 * @return {Element} element
 */
function make(tag) {

  // ...stuff...

  return element;
}

  • 17.2 Use // for single line comments. Place single line comments on a newline above the subject of the comment. Put an empty line before the comment unless it's on the first line of a block.

    // bad
const active = true;  // is current tab

// good
// is current tab
const active = true;

// bad
function getType() {
  console.log('fetching type...');
  // set the default type to 'no type'
  const type = this._type || 'no type';

  return type;
}

// good
function getType() {
  console.log('fetching type...');

  // set the default type to 'no type'
  const type = this._type || 'no type';

  return type;
}

// also good
function getType() {
  // set the default type to 'no type'
  const type = this._type || 'no type';

  return type;
}

  • 17.3 Prefixing your comments with FIXME or TODO helps other developers quickly understand if you're pointing out a problem that needs to be revisited, or if you're suggesting a solution to the problem that needs to be implemented. These are different than regular comments because they are actionable. The actions are FIXME: -- need to figure this out or TODO: -- need to implement.

  • 17.4 Use // FIXME: to annotate problems.

    class Calculator extends Abacus {
  constructor() {
    super();

    // FIXME: shouldn't use a global here
    total = 0;
  }
}

  • 17.5 Use // TODO: to annotate solutions to problems.

    class Calculator extends Abacus {
  constructor() {
    super();

    // TODO: total should be configurable by an options param
    this.total = 0;
  }
}

⬆ 回到顶部

Whitespace

  • 18.1 Use soft tabs set to 2 spaces. eslint: indent jscs: validateIndentation

    // bad
function foo() {
∙∙∙∙const name;
}

// bad
function bar() {
∙const name;
}

// good
function baz() {
∙∙const name;
}

  • 18.2 Place 1 space before the leading brace. eslint: space-before-blocks jscs: requireSpaceBeforeBlockStatements

    // bad
function test(){
  console.log('test');
}

// good
function test() {
  console.log('test');
}

// bad
dog.set('attr',{
  age: '1 year',
  breed: 'Bernese Mountain Dog',
});

// good
dog.set('attr', {
  age: '1 year',
  breed: 'Bernese Mountain Dog',
});

  • 18.3 Place 1 space before the opening parenthesis in control statements (if, while etc.). Place no space between the argument list and the function name in function calls and declarations. eslint: keyword-spacing jscs: requireSpaceAfterKeywords

    // bad
if(isJedi) {
  fight ();
}

// good
if (isJedi) {
  fight();
}

// bad
function fight () {
  console.log ('Swooosh!');
}

// good
function fight() {
  console.log('Swooosh!');
}

  • 18.5 End files with a single newline character.

    // bad
(function (global) {
  // ...stuff...
})(this);
    // bad
(function (global) {
  // ...stuff...
})(this);↵
↵
    // good
(function (global) {
  // ...stuff...
})(this);↵

  • 18.6 Use indentation when making long method chains (more than 2 method chains). Use a leading dot, which emphasizes that the line is a method call, not a new statement. eslint: newline-per-chained-call no-whitespace-before-property

    // bad
$('#items').find('.selected').highlight().end().find('.open').updateCount();

// bad
$('#items').
  find('.selected').
    highlight().
    end().
  find('.open').
    updateCount();

// good
$('#items')
  .find('.selected')
    .highlight()
    .end()
  .find('.open')
    .updateCount();

// bad
const leds = stage.selectAll('.led').data(data).enter().append('svg:svg').classed('led', true)
    .attr('width', (radius + margin) * 2).append('svg:g')
    .a
10000
ttr('transform', 'translate(' + (radius + margin) + ',' + (radius + margin) + ')')
    .call(tron.led);

// good
const leds = stage.selectAll('.led')
    .data(data)
  .enter().append('svg:svg')
    .classed('led', true)
    .attr('width', (radius + margin) * 2)
  .append('svg:g')
    .attr('transform', 'translate(' + (radius + margin) + ',' + (radius + margin) + ')')
    .call(tron.led);

// good
const leds = stage.selectAll('.led').data(data);

  • 18.7 Leave a blank line after blocks and before the next statement. jscs: requirePaddingNewLinesAfterBlocks

    // bad
if (foo) {
  return bar;
}
return baz;

// good
if (foo) {
  return bar;
}

return baz;

// bad
const obj = {
  foo() {
  },
  bar() {
  },
};
return obj;

// good
const obj = {
  foo() {
  },

  bar() {
  },
};

return obj;

// bad
const arr = [
  function foo() {
  },
  function bar() {
  },
];
return arr;

// good
const arr = [
  function foo() {
  },

  function bar() {
  },
];

return arr;

  • 18.8 Do not pad your blocks with blank lines. eslint: padded-blocks jscs: disallowPaddingNewlinesInBlocks

    // bad
function bar() {

  console.log(foo);

}

// also bad
if (baz) {

  console.log(qux);
} else {
  console.log(foo);

}

// good
function bar() {
  console.log(foo);
}

// good
if (baz) {
  console.log(qux);
} else {
  console.log(foo);
}

  • 18.9 Do not add spaces inside parentheses. eslint: space-in-parens jscs: disallowSpacesInsideParentheses

    // bad
function bar( foo ) {
  return foo;
}

// good
function bar(foo) {
  return foo;
}

// bad
if ( foo ) {
  console.log(foo);
}

// good
if (foo) {
  console.log(foo);
}

  • 18.12 Avoid having lines of code that are longer than 100 characters (including whitespace). eslint: max-len jscs: maximumLineLength

    Why? This ensures readability and maintainability.

    // bad
const foo = 'Whatever national crop flips the window. The cartoon reverts within the screw. Whatever wizard constrains a helpful ally. The counterpart ascends!';

// bad
$.ajax({ method: 'POST', url: 'https://airbnb.com/', data: { name: 'John' } }).done(() => console.log('Congratulations!')).fail(() => console.log('You have failed this city.'));

// good
const foo = 'Whatever national crop flips the window. The cartoon reverts within the screw. ' +
  'Whatever wizard constrains a helpful ally. The counterpart ascends!';

// good
$.ajax({
  method: 'POST',
  url: 'https://airbnb.com/',
  data: { name: 'John' },
})
  .done(() => console.log('Congratulations!'))
  .fail(() => console.log('You have failed this city.'));

⬆ 回到顶部

Commas

  • 19.1 Leading commas: Nope. eslint: comma-style jscs: requireCommaBeforeLineBreak

    // bad
const story = [
    once
  , upon
  , aTime
];

// good
const story = [
  once,
  upon,
  aTime,
];

// bad
const hero = {
    firstName: 'Ada'
  , lastName: 'Lovelace'
  , birthYear: 1815
  , superPower: 'computers'
};

// good
const hero = {
  firstName: 'Ada',
  lastName: 'Lovelace',
  birthYear: 1815,
  superPower: 'computers',
};

  • 19.2 Additional trailing comma: Yup. eslint: comma-dangle jscs: requireTrailingComma

    Why? This leads to cleaner git diffs. Also, transpilers like Babel will remove the additional trailing comma in the transpiled code which means you don't have to worry about the trailing comma problem in legacy browsers.

    // bad - git diff without trailing comma
const hero = {
     firstName: 'Florence',
-    lastName: 'Nightingale'
+    lastName: 'Nightingale',
+    inventorOf: ['coxcomb chart', 'modern nursing']
};

// good - git diff with trailing comma
const hero = {
     firstName: 'Florence',
     lastName: 'Nightingale',
+    inventorOf: ['coxcomb chart', 'modern nursing'],
};

// bad
const hero = {
  firstName: 'Dana',
  lastName: 'Scully'
};

const heroes = [
  'Batman',
  'Superman'
];

// good
const hero = {
  firstName: 'Dana',
  lastName: 'Scully',
};

const heroes = [
  'Batman',
  'Superman',
];

⬆ 回到顶部

Semicolons

  • 20.1 Yup. eslint: semi jscs: requireSemicolons

    // bad
(function () {
  const name = 'Skywalker'
  return name
})()

// good
(function () {
  const name = 'Skywalker';
  return name;
}());

// good, but legacy (guards against the function becoming an argument when two files with IIFEs are concatenated)
;(() => {
  const name = 'Skywalker';
  return name;
}());

    Read more.

⬆ 回到顶部

Type Casting & Coercion

  • 21.1 Perform type coercion at the beginning of the statement.

  • 21.2 Strings:

    // => this.reviewScore = 9;

// bad
const totalScore = this.reviewScore + ''; // invokes this.reviewScore.valueOf()

// bad
const totalScore = this.reviewScore.toString(); // isn't guaranteed to return a string

// good
const totalScore = String(this.reviewScore);

  • 21.3 Numbers: Use Number for type casting and parseInt always with a radix for parsing strings. eslint: radix

    const inputValue = '4';

// bad
const val = new Number(inputValue);

// bad
const val = +inputValue;

// bad
const val = inputValue >> 0;

// bad
const val = parseInt(inputValue);

// good
const val = Number(inputValue);

// good
const val = parseInt(inputValue, 10);

  • 21.4 If for whatever reason you are doing something wild and parseInt is your bottleneck and need to use Bitshift for performance reasons, leave a comment explaining why and what you're doing.

    // good
/**
 * parseInt was the reason my code was slow.
 * Bitshifting the String to coerce it to a
 * Number made it a lot faster.
 */
const val = inputValue >> 0;

  • 21.5 Note: Be careful when using bitshift operations. Numbers are represented as 64-bit values, but bitshift operations always return a 32-bit integer (source). Bitshift can lead to unexpected behavior for integer values larger than 32 bits. Discussion. Largest signed 32-bit Int is 2,147,483,647:

    2147483647 >> 0 //=> 2147483647
2147483648 >> 0 //=> -2147483648
2147483649 >> 0 //=> -2147483647

  • 21.6 Booleans:

    const age = 0;

// bad
const hasAge = new Boolean(age);

// good
const hasAge = Boolean(age);

// best
const hasAge = !!age;

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Naming Conventions

  • 22.1 Avoid single letter names. Be descriptive with your naming.

    // bad
function q() {
  // ...stuff...
}

// good
function query() {
  // ..stuff..
}

  • 22.2 Use camelCase when naming objects, functions, and instances. eslint: camelcase jscs: requireCamelCaseOrUpperCaseIdentifiers

    // bad
const OBJEcttsssss = {};
const this_is_my_object = {};
function c() {}

// good
const thisIsMyObject = {};
function thisIsMyFunction() {}

  • 22.3 Use PascalCase only when naming constructors or classes. eslint: new-cap jscs: requireCapitalizedConstructors

    // bad
function user(options) {
  this.name = options.name;
}

const bad = new user({
  name: 'nope',
});

// good
class User {
  constructor(options) {
    this.name = options.name;
  }
}

const good = new User({
  name: 'yup',
});

  • 22.4 Do not use trailing or leading underscores. eslint: no-underscore-dangle jscs: disallowDanglingUnderscores

    Why? JavaScript does not have the concept of privacy in terms of properties or methods. Although a leading underscore is a common convention to mean “private”, in fact, these properties are fully public, and as such, are part of your public API contract. This convention might lead developers to wrongly think that a change won't count as breaking, or that tests aren't needed. tl;dr: if you want something to be “private”, it must not be observably present.

    // bad
this.__firstName__ = 'Panda';
this.firstName_ = 'Panda';
this._firstName = 'Panda';

// good
this.firstName = 'Panda';

  • 22.5 Don't save references to this. Use arrow functions or Function#bind. jscs: disallowNodeTypes

    // bad
function foo() {
  const self = this;
  return function () {
    console.log(self);
  };
}

// bad
function foo() {
  const that = this;
  return function () {
    console.log(that);
  };
}

// good
function foo() {
  return () => {
    console.log(this);
  };
}

  • 22.6 A base filename should exactly match the name of its default export.

    // file 1 contents
class CheckBox {
  // ...
}
export default CheckBox;

// file 2 contents
export default function fortyTwo() { return 42; }

// file 3 contents
export default function insideDirectory() {}

// in some other file
// bad
import CheckBox from './checkBox'; // PascalCase import/export, camelCase filename
import FortyTwo from './FortyTwo'; // PascalCase import/filename, camelCase export
import InsideDirectory from './InsideDirectory'; // PascalCase import/filename, camelCase export

// bad
import CheckBox from './check_box'; // PascalCase import/export, snake_case filename
import forty_two from './forty_two'; // snake_case import/filename, camelCase export
import inside_directory from './inside_directory'; // snake_case import, camelCase export
import index from './inside_directory/index'; // requiring the index file explicitly
import insideDirectory from './insideDirectory/index'; // requiring the index file explicitly

// good
import CheckBox from './CheckBox'; // PascalCase export/import/filename
import fortyTwo from './fortyTwo'; // camelCase export/import/filename
import insideDirectory from './insideDirectory'; // camelCase export/import/directory name/implicit "index"
// ^ supports both insideDirectory.js and insideDirectory/index.js

  • 22.7 Use camelCase when you export-default a function. Your filename should be identical to your function's name.

    function makeStyleGuide() {
}

export default makeStyleGuide;

  • 22.8 Use PascalCase when you export a constructor / class / singleton / function library / bare object.

    const AirbnbStyleGuide = {
  es6: {
  }
};

export default AirbnbStyleGuide;

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Accessors

  • 23.1 Accessor functions for properties are not required.

  • 23.2 Do not use JavaScript getters/setters as they cause unexpected side effects and are harder to test, maintain, and reason about. Instead, if you do make accessor functions, use getVal() and setVal('hello').

    // bad
class Dragon {
  get age() {
    // ...
  }

  set age(value) {
    // ...
  }
}

// good
class Dragon {
  getAge() {
    // ...
  }

  setAge(value) {
    // ...
  }
}

  • 23.3 If the property/method is a boolean, use isVal() or hasVal().

    // bad
if (!dragon.age()) {
  return false;
}

// good
if (!dragon.hasAge()) {
  return false;
}

  • 23.4 It's okay to create get() and set() functions, but be consistent.

    class Jedi {
  constructor(options = {}) {
    const lightsaber = options.lightsaber || 'blue';
    this.set('lightsaber', lightsaber);
  }

  set(key, val) {
    this[key] = val;
  }

  get(key) {
    return this[key];
  }
}

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Events

  • 24.1 When attaching data payloads to events (whether DOM events or something more proprietary like Backbone events), pass a hash instead of a raw value. This allows a subsequent contributor to add more data to the event payload without finding and updating every handler for the event. For example, instead of:

    // bad
$(this).trigger('listingUpdated', listing.id);

...

$(this).on('listingUpdated', (e, listingId) => {
  // do something with listingId
});

    prefer:

    // good
$(this).trigger('listingUpdated', { listingId: listing.id });

...

$(this).on('listingUpdated', (e, data) => {
  // do something with data.listingId
});

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jQuery

  • 25.1 Prefix jQuery object variables with a $. jscs: requireDollarBeforejQueryAssignment

    // bad
const sidebar = $('.sidebar');

// good
const $sidebar = $('.sidebar');

// good
const $sidebarBtn = $('.sidebar-btn');

  • 25.2 Cache jQuery lookups.

    // bad
function setSidebar() {
  $('.sidebar').hide();

  // ...stuff...

  $('.sidebar').css({
    'background-color': 'pink'
  });
}

// good
function setSidebar() {
  const $sidebar = $('.sidebar');
  $sidebar.hide();

  // ...stuff...

  $sidebar.css({
    'background-color': 'pink'
  });
}

  • 25.3 For DOM queries use Cascading $('.sidebar ul') or parent > child $('.sidebar > ul'). jsPerf

  • 25.4 Use find with scoped jQuery object queries.

    // bad
$('ul', '.sidebar').hide();

// bad
$('.sidebar').find('ul').hide();

// good
$('.sidebar ul').hide();

// good
$('.sidebar > ul').hide();

// good
$sidebar.find('ul').hide();

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ECMAScript 5 Compatibility

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ECMAScript 6 Styles

  • 27.1 This is a collection of links to the various ES6 features.
  1. Arrow Functions
  2. Classes
  3. Object Shorthand
  4. Object Concise
  5. Object Computed Properties
  6. Template Strings
  7. Destructuring
  8. Default Parameters
  9. Rest
  10. Array Spreads
  11. Let and Const
  12. Iterators and Generators
  13. Modules

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Testing

  • 28.1 Yup.

    function foo() {
  return true;
}

  • 28.2 No, but seriously:
  • Whichever testing framework you use, you should be writing tests!
  • Strive to write many small pure functions, and minimize where mutations occur.
  • Be cautious about stubs and mocks - they can make your tests more brittle.
  • We primarily use mocha at Airbnb. tape is also used occasionally for small, separate modules.
  • 100% test coverage is a good goal to strive for, even if it's not always practical to reach it.
  • Whenever you fix a bug, write a regression test. A bug fixed without a regression test is almost certainly going to break again in the future.

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Performance

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Resources

Learning ES6

Read This

Tools

Other Style Guides

Other Styles

Further Reading

Books

Blogs

Podcasts

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In the Wild

This is a list of organizations that are using this style guide. Send us a pull request and we'll add you to the list.

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Translation

This style guide is also available in other languages:

The JavaScript Style Guide Guide

Chat With Us About JavaScript

Contributors

License

(The MIT License)

Copyright (c) 2014-2016 Airbnb

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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Amendments

We encourage you to fork this guide and change the rules to fit your team's style guide. Below, you may list some amendments to the style guide. This allows you to periodically update your style guide without having to deal with merge conflicts.

};

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