一、前言
规范的目的是为了编写高质量的代码,让我们和同事们每天得心情都是愉悦的,大家在一起合作是快乐的。
温馨提示:这些规范不会让你立刻变成一个优秀的工程师,长期坚持规范编码也并不意味着你今后就不会再犯错。千里之行,始于足下。我们要经常和同事们进行代码评审,不断优化自己的代码。不要惧怕改善代码质量所需付出的努力,加油。
二、命名
2.1 项目命名
全部采用小写方式,以下划线(或中划线)分隔。
例:taro-v2ex-hooks
、taro_v2ex_hooks
2.2 目录命名
全部采用小写方式, 以下划线(或中划线)分隔,有复数结构时,要采用复数命名法, 缩写不用复数。
例:styles
、utils
、img
、demo_styles
温馨提示:统一风格,不要一会儿用中划线,一会儿下划线。
2.3 命名严谨性
代码中的命名严禁使用拼音与英文混合的方式,纯拼音也要避免。国际通用的名称,可视同英文。
正例:shenzhen
、rmb
反例:getGuoJiaName()
三、HTML
3.1 语法
- 缩进使用 2 个空格(或者 4 个空格)
- 嵌套的节点应该缩进
- 优先使用语义化标签
- 在属性上,使用双引号
例:
<!DOCTYPE html>
<html>
<head>
<title>Page title</title>
</head>
<body>
<header></header>
<img src="images/company_logo.png" alt="Company">
<h1 class="hello-world">Hello, world!</h1>
<footer></footer>
</body>
</html>
3.2 属性顺序
属性应该按照特定的顺序出现以保证易读性。
- class
- id
- name
- data-*
- src, for, type, href, value , max-length, max, min, pattern
- placeholder, title, alt
- aria-*, role
- required, readonly, disabled
class 是为高可复用组件设计的,所以应处在第一位。
id 更加具体且应该尽量少使用,所以将它放在第二位。
例:<a class="..." id="..." data-modal="toggle" href="#">Example link</a>
四、CSS
4.1 命名
- 类名使用小写字母,以中划线(或下划线)分隔
- id 采用驼峰式命名
- scss 中的变量、函数、混合、placeholder 采用驼峰式命名
例:
#myApp {
font-weight: 400;
}
.hello-world {
font-size: 24px;
}
4.2 空格
- 属性值前
- 选择器
>
,+
,~
前后 {
前!important
中!
前@else
前后- 属性值中的
,
后 - 注释
/*
后和*/
前
例:
/* good */
.element {
color: red !important;
background-color: rgba(0, 0, 0, .5);
}
@if {
...
} @else {
...
}
4.3 空行
- 文件最后保留一个空行
}
后最好跟一个空行,包括 scss 中嵌套的规则- 属性之间需要适当的空行,具体见属性声明顺序
例:
.element {
...
}
.dialog {
color: red;
&:after {
...
}
}
4.4 换行
{
后和}
前- 每个属性独占一行
- 多个规则的分隔符
,
后
例:
.element {
color: red;
background-color: black;
}
.main,
.dialog {
...
}
4.5 属性声明顺序
相关的属性声明按右边的顺序做分组处理,组之间需要有一个空行。
例:
.declaration-order {
display: block;
float: right;
position: absolute;
top: 0;
right: 0;
bottom: 0;
left: 0;
z-index: 100;
border: 1px solid #e5e5e5;
border-radius: 3px;
width: 100px;
height: 100px;
font: normal 13px "Helvetica Neue", sans-serif;
line-height: 1.5;
text-align: center;
color: #333;
background-color: #f5f5f5;
opacity: 1;
}
下面是推荐的属性的顺序:
[
[
"display",
"visibility",
"float",
"clear",
"overflow",
"overflow-x",
"overflow-y",
"clip",
"zoom"
],
[
"table-layout",
"empty-cells",
"caption-side",
"border-spacing",
"border-collapse",
"list-style",
"list-style-position",
"list-style-type",
"list-style-image"
],
[
"-webkit-box-orient",
"-webkit-box-direction",
"-webkit-box-decoration-break",
"-webkit-box-pack",
"-webkit-box-align",
"-webkit-box-flex"
],
[
"position",
"top",
"right",
"bottom",
"left",
"z-index"
],
[
"margin",
"margin-top",
"margin-right",
"margin-bottom",
"margin-left",
"-webkit-box-sizing",
"-moz-box-sizing",
"box-sizing",
"border",
"border-width",
"border-style",
"border-color",
"border-top",
"border-top-width",
"border-top-style",
"border-top-color",
"border-right",
"border-right-width",
"border-right-style",
"border-right-color",
"border-bottom",
"border-bottom-width",
"border-bottom-style",
"border-bottom-color",
"border-left",
"border-left-width",
"border-left-style",
"border-left-color",
"-webkit-border-radius",
"-moz-border-radius",
"border-radius",
"-webkit-border-top-left-radius",
"-moz-border-radius-topleft",
"border-top-left-radius",
"-webkit-border-top-right-radius",
"-moz-border-radius-topright",
"border-top-right-radius",
"-webkit-border-bottom-right-radius",
"-moz-border-radius-bottomright",
"border-bottom-right-radius",
"-webkit-border-bottom-left-radius",
"-moz-border-radius-bottomleft",
"border-bottom-left-radius",
"-webkit-border-image",
"-moz-border-image",
"-o-border-image",
"border-image",
"-webkit-border-image-source",
"-moz-border-image-source",
"-o-border-image-source",
"border-image-source",
"-webkit-border-image-slice",
"-moz-border-image-slice",
"-o-border-image-slice",
"border-image-slice",
"-webkit-border-image-width",
"-moz-border-image-width",
"-o-border-image-width",
"border-image-width",
"-webkit-border-image-outset",
"-moz-border-image-outset",
"-o-border-image-outset",
"border-image-outset",
"-webkit-border-image-repeat",
"-moz-border-image-repeat",
"-o-border-image-repeat",
"border-image-repeat",
"padding",
"padding-top",
"padding-right",
"padding-bottom",
"padding-left",
"width",
"min-width",
"max-width",
"height",
"min-height",
"max-height"
],
[
"font",
"font-family",
"font-size",
"font-weight",
"font-style",
"font-variant",
"font-size-adjust",
"font-stretch",
"font-effect",
"font-emphasize",
"font-emphasize-position",
"font-emphasize-style",
"font-smooth",
"line-height",
"text-align",
"-webkit-text-align-last",
"-moz-text-align-last",
"-ms-text-align-last",
"text-align-last",
"vertical-align",
"white-space",
"text-decoration",
"text-emphasis",
"text-emphasis-color",
"text-emphasis-style",
"text-emphasis-position",
"text-indent",
"-ms-text-justify",
"text-justify",
"letter-spacing",
"word-spacing",
"-ms-writing-mode",
"text-outline",
"text-transform",
"text-wrap",
"-ms-text-overflow",
"text-overflow",
"text-overflow-ellipsis",
"text-overflow-mode",
"-ms-word-wrap",
"word-wrap",
"-ms-word-break",
"word-break"
],
[
"color",
"background",
"filter:progid:DXImageTransform.Microsoft.AlphaImageLoader",
"background-color",
"background-image",
"background-repeat",
"background-attachment",
"background-position",
"-ms-background-position-x",
"background-position-x",
"-ms-background-position-y",
"background-position-y",
"-webkit-background-clip",
"-moz-background-clip",
"background-clip",
"background-origin",
"-webkit-background-size",
"-moz-background-size",
"-o-background-size",
"background-size"
],
[
"outline",
"outline-width",
"outline-style",
"outline-color",
"outline-offset",
"opacity",
"filter:progid:DXImageTransform.Microsoft.Alpha(Opacity",
"-ms-filter:\\'progid:DXImageTransform.Microsoft.Alpha",
"-ms-interpolation-mode",
"-webkit-box-shadow",
"-moz-box-shadow",
"box-shadow",
"filter:progid:DXImageTransform.Microsoft.gradient",
"-ms-filter:\\'progid:DXImageTransform.Microsoft.gradient",
"text-shadow"
],
[
"-webkit-transition",
"-moz-transition",
"-ms-transition",
"-o-transition",
"transition",
"-webkit-transition-delay",
"-moz-transition-delay",
"-ms-transition-delay",
"-o-transition-delay",
"transition-delay",
"-webkit-transition-timing-function",
"-moz-transition-timing-function",
"-ms-transition-timing-function",
"-o-transition-timing-function",
"transition-timing-function",
"-webkit-transition-duration",
"-moz-transition-duration",
"-ms-transition-duration",
"-o-transition-duration",
"transition-duration",
"-webkit-transition-property",
"-moz-transition-property",
"-ms-transition-property",
"-o-transition-property",
"transition-property",
"-webkit-transform",
"-moz-transform",
"-ms-transform",
"-o-transform",
"transform",
"-webkit-transform-origin",
"-moz-transform-origin",
"-ms-transform-origin",
"-o-transform-origin",
"transform-origin",
"-webkit-animation",
"-moz-animation",
"-ms-animation",
"-o-animation",
"animation",
"-webkit-animation-name",
"-moz-animation-name",
"-ms-animation-name",
"-o-animation-name",
"animation-name",
"-webkit-animation-duration",
"-moz-animation-duration",
"-ms-animation-duration",
"-o-animation-duration",
"animation-duration",
"-webkit-animation-play-state",
"-moz-animation-play-state",
"-ms-animation-play-state",
"-o-animation-play-state",
"animation-play-state",
"-webkit-animation-timing-function",
"-moz-animation-timing-function",
"-ms-animation-timing-function",
"-o-animation-timing-function",
"animation-timing-function",
"-webkit-animation-delay",
"-moz-animation-delay",
"-ms-animation-delay",
"-o-animation-delay",
"animation-delay",
"-webkit-animation-iteration-count",
"-moz-animation-iteration-count",
"-ms-animation-iteration-count",
"-o-animation-iteration-count",
"animation-iteration-count",
"-webkit-animation-direction",
"-moz-animation-direction",
"-ms-animation-direction",
"-o-animation-direction",
"animation-direction"
],
[
"content",
"quotes",
"counter-reset",
"counter-increment",
"resize",
"cursor",
"-webkit-user-select",
"-moz-user-select",
"-ms-user-select",
"user-select",
"nav-index",
"nav-up",
"nav-right",
"nav-down",
"nav-left",
"-moz-tab-size",
"-o-tab-size",
"tab-size",
"-webkit-hyphens",
"-moz-hyphens",
"hyphens",
"pointer-events"
]
]
4.6 属性简写
属性简写需要你非常清楚属性值的正确顺序,而且在大多数情况下并不需要设置属性简写中包含的所有值,所以建议尽量分开声明会更加清晰。
常见的属性简写包括:
- font
- background
- transition
- animation
例:
.element {
transition-delay: 2s;
transition-timing-function: linear;
transition-duration: 1s;
transition-property: opacity;
}
五、JavaScript
5.1 变量
5.1.1 使用有意义,可读性好的变量名
反例:
var yyyymmdstr = moment().format('YYYY/MM/DD');
正例:
var yearMonthDay = moment().format('YYYY/MM/DD');
5.1.2 使用 ES6 的 const 定义常量
反例中使用"var"定义的"常量"是可变的。
在声明一个常量时,该常量在整个程序中都应该是不可变的。
反例:
var FIRST_US_PRESIDENT = "George Washington";
正例:
const FIRST_US_PRESIDENT = "George Washington";
5.1.3 使用易于检索名称
我们需要阅读的代码远比自己写的要多,使代码拥有良好的可读性且易于检索非常重要。阅读变量名晦涩难懂的代码对读者来说是一种相当糟糕的体验。 让你的变量名易于检索。
反例:
// 525600 是什么?
for (var i = 0; i < 525600; i++) {
runCronJob();
}
正例:
const MINUTES_IN_A_YEAR = 525600;
for (var i = 0; i < MINUTES_IN_A_YEAR; i++) {
runCronJob();
}
5.1.4 显式优于隐式
反例:
var locations = ['Austin', 'New York', 'San Francisco'];
locations.forEach((l) => {
doStuff();
doSomeOtherStuff();
...
...
...
// l 是什么?
dispatch(l);
});
正例:
var locations = ['Austin', 'New York', 'San Francisco'];
locations.forEach((location) => {
doStuff();
doSomeOtherStuff();
...
...
...
dispatch(location);
});
5.1.5 避免无意义的条件判断
反例:
function createMicrobrewery(name) {
var breweryName;
if (name) {
breweryName = name;
} else {
breweryName = 'Hipster Brew Co.';
}
}
正例:
function createMicrobrewery(name) {
var breweryName = name || 'Hipster Brew Co.'
}
5.2 函数
5.2.1 函数参数
限制函数参数数量(理想情况下应不超过 2 个)很有必要,这么做使得在测试函数时更加轻松。过多的参数将导致难以采用有效的测试用例对函数的各个参数进行测试。
应避免三个以上参数的函数。通常情况下,参数超过两个意味着函数功能过于复杂,这时需要重新优化你的函数。当确实需要多个参数时,大多情况下可以考虑这些参数封装成一个对象。
JS 定义对象非常方便,当需要多个参数时,可以使用一个对象进行替代。
反例:
function createMenu(title, body, buttonText, cancellable) {
...
}
正例:
var menuConfig = {
title: 'Foo',
body: 'Bar',
buttonText: 'Baz',
cancellable: true
}
function createMenu(menuConfig) {
...
}
5.2.2 函数功能的单一性
这是软件功能中最重要的原则之一。
功能不单一的函数将导致难以重构、测试和理解。功能单一的函数易于重构,并使代码更加干净。
反例:
function emailClients(clients) {
clients.forEach(client => {
let clientRecord = database.lookup(client);
if (clientRecord.isActive()) {
email(client);
}
});
}
正例:
function emailClients(clients) {
clients.forEach(client => {
emailClientIfNeeded(client);
});
}
function emailClientIfNeeded(client) {
if (isClientActive(client)) {
email(client);
}
}
function isClientActive(client) {
let clientRecord = database.lookup(client);
return clientRecord.isActive();
}
5.2.3 移除重复的代码
永远、永远、永远不要在任何循环下有重复的代码。
这种做法毫无意义且潜在危险极大。重复的代码意味着逻辑变化时需要对不止一处进行修改。JS 弱类型的特点使得函数拥有更强的普适性。好好利用这一优点吧。
反例:
function showDeveloperList(developers) {
developers.forEach(developer => {
var expectedSalary = developer.calculateExpectedSalary();
var experience = developer.getExperience();
var githubLink = developer.getGithubLink();
var data = {
expectedSalary: expectedSalary,
experience: experience,
githubLink: githubLink
};
render(data);
});
}
function showManagerList(managers) {
managers.forEach(manager => {
var expectedSalary = manager.calculateExpectedSalary();
var experience = manager.getExperience();
var portfolio = manager.getMBAProjects();
var data = {
expectedSalary: expectedSalary,
experience: experience,
portfolio: portfolio
};
render(data);
});
}
正例:
function showList(employees) {
employees.forEach(employee => {
var expectedSalary = employee.calculateExpectedSalary();
var experience = employee.getExperience();
var portfolio;
if (employee.type === 'manager') {
portfolio = employee.getMBAProjects();
} else {
portfolio = employee.getGithubLink();
}
var data = {
expectedSalary: expectedSalary,
experience: experience,
portfolio: portfolio
};
render(data);
});
}
5.2.4 采用默认参数精简代码
反例:
function writeForumComment(subject, body) {
subject = subject || 'No Subject';
body = body || 'No text';
}
正例:
function writeForumComment(subject = 'No subject', body = 'No text') {
...
}
5.2.5 不要使用 Flag 作为函数参数
这通常意味着函数的功能的单一性已经被破坏。此时应考虑对函数进行再次划分。
反例:
function createFile(name, temp) {
if (temp) {
fs.create('./temp/' + name);
} else {
fs.create(name);
}
}
正例:
function createTempFile(name) {
fs.create('./temp/' + name);
}
function createFile(name) {
fs.create(name);
}
5.2.6 采用函数式编程
函数式的编程具有更干净且便于测试的特点。尽可能的使用这种风格吧。
反例:
const programmerOutput = [
{
name: 'Uncle Bobby',
linesOfCode: 500
}, {
name: 'Suzie Q',
linesOfCode: 1500
}, {
name: 'Jimmy Gosling',
linesOfCode: 150
}, {
name: 'Gracie Hopper',
linesOfCode: 1000
}
];
var totalOutput = 0;
for (var i = 0; i < programmerOutput.length; i++) {
totalOutput += programmerOutput[i].linesOfCode;
}
正例:
const programmerOutput = [
{
name: 'Uncle Bobby',
linesOfCode: 500
}, {
name: 'Suzie Q',
linesOfCode: 1500
}, {
name: 'Jimmy Gosling',
linesOfCode: 150
}, {
name: 'Gracie Hopper',
linesOfCode: 1000
}
];
var totalOutput = programmerOutput
.map((programmer) => programmer.linesOfCode)
.reduce((acc, linesOfCode) => acc + linesOfCode, 0);
5.2.7 避免过度优化
现代的浏览器在运行时会对代码自动进行优化。有时人为对代码进行优化可能是在浪费时间。
反例:
// 这里使用变量 len 是因为在老式浏览器中,直接使用正例中的方式会导致每次循环均重复计算 list.length 的值,
// 而在现代浏览器中会自动完成优化,这一行为是没有必要的
for (var i = 0, len = list.length; i < len; i++) {
// ...
}
正例:
for (var i = 0; i < list.length; i++) {
// ...
}
5.3 并发
5.3.1 用 Promises 替代回调
回调不够整洁并会造成大量的嵌套。ES6 内嵌了 Promises,使用它吧。
反例:
require('request').get('https://en.wikipedia.org/wiki/Robert_Cecil_Martin', function(err, response) {
if (err) {
console.error(err);
}
else {
require('fs').writeFile('article.html', response.body, function(err) {
if (err) {
console.error(err);
} else {
console.log('File written');
}
})
}
})
正例:
require('request-promise').get('https://en.wikipedia.org/wiki/Robert_Cecil_Martin')
.then(function(response) {
return require('fs-promise').writeFile('article.html', response);
})
.then(function() {
console.log('File written');
})
.catch(function(err) {
console.error(err);
})
5.3.2 Async/Await 是较 Promises 更好的选择
Promises 是较回调而言更好的一种选择,但 ES7 中的 async 和 await 更胜过 Promises。
在能使用 ES7 特性的情况下可以尽量使用他们替代 Promises。
反例:
require('request-promise').get('https://en.wikipedia.org/wiki/Robert_Cecil_Martin')
.then(function(response) {
return require('fs-promise').writeFile('article.html', response);
})
.then(function() {
console.log('File written');
})
.catch(function(err) {
console.error(err);
})
正例:
async function getCleanCodeArticle() {
try {
var request = await require('request-promise')
var response = await request.get('https://en.wikipedia.org/wiki/Robert_Cecil_Martin');
var fileHandle = await require('fs-promise');
await fileHandle.writeFile('article.html', response);
console.log('File written');
} catch(err) {
console.log(err);
}
}
5.4 注释
5.4.1 只对存在一定业务逻辑复杂性的代码进行注释
注释并不是必须的,好的代码是能够让人一目了然,不用过多无谓的注释。
反例:
function hashIt(data) {
// The hash
var hash = 0;
// Length of string
var length = data.length;
// Loop through every character in data
for (var i = 0; i < length; i++) {
// Get character code.
var char = data.charCodeAt(i);
// Make the hash
hash = ((hash << 5) - hash) + char;
// Convert to 32-bit integer
hash = hash & hash;
}
}
正例:
function hashIt(data) {
var hash = 0;
var length = data.length;
for (var i = 0; i < length; i++) {
var char = data.charCodeAt(i);
hash = ((hash << 5) - hash) + char;
// Convert to 32-bit integer
hash = hash & hash;
}
}
5.4.2 不要在代码库中遗留被注释掉的代码
版本控制的存在是有原因的。让旧代码存在于你的 history 里吧。
反例:
doStuff();
// doOtherStuff();
// doSomeMoreStuff();
// doSoMuchStuff();
正例:
doStuff();
六、参考文章
七、感谢
- 如果本文对你有帮助,就点个赞支持下吧!感谢阅读。