eslint — js书写规范

一、安装
npm install -g eslint 安装eslint
编辑器安装插件eslint（具体安装方法根据不同编辑器而不同）

二、使用
使用方法一：
eslint --init npm中用命令新建eslintrc.js文件
eslint yourfile.js npm中用命令检查自己文件中的错误

使用方法二：
手动在项目的根目录下新建eslintrc.*文件（.js、.json、.yaml、.yml等），进行配置（具体配置规则详见下文），即可在安装好eslint的编辑器中查看到出现错误的位置。

三、配置：http://eslint.org/docs/rules/ (以下规则文件配置一个即可，置于项目根目录下)
(1).eslintrc文件中进行配置 http://eslint.org/docs/user-guide/configuring

{
    "rules": {
        "semi": ["error", "always"],
        "quotes": ["error", "double"]
    }
}

四、其他
1.在样式之前标注“/* eslint-disable */”，可忽略配置的规则；标注“/* esint-enable */“，开启配置的规则
2.“/* eslint-enable */“必须在“/* eslint-disable */”之后使用
3.忽略指定的内容：新建一个.eslineignore文件，例如：
# /node_modules/* and /bower_components/* ignored by default
# Ignore built files except build/index.js
build/*
!build/index.js
通过命令 eslint --ignore-path .eslintignore file.js可检测是否被忽视
4.enlint 有很多的rules，为了改变rule的设置，可以设置rule ID等同于一些规则属性：如
"off" or 0 关闭规则
"warn" or 1 打开规则，出现警告提示
"error" or 2 打开规则，出现错误提示
规则可如下定义：

"rules": {
    "camel_case": 2
  }

五、配置文件

{
    "rules": {
    "array-callback-return": "error",
    "indent": ["error", 4, {"SwitchCase": 1}],
    "block-spacing": "error",
    "brace-style": ["error", "1tbs"],
    "camelcase": ["error", { "properties": "never" }],
    "callback-return": ["error", ["cb", "callback", "next"]],
    "comma-spacing": "error",
    "comma-style": ["error", "last"],
    "consistent-return": "error",
    "curly": ["error", "all"],
    "default-case": "error",
    "dot-notation": ["error", { "allowKeywords": false }],
    "eol-last": "error",
    "eqeqeq": "error",
    "guard-for-in": "error",
    "key-spacing": ["error", { "beforeColon": false, "afterColon": true }],
    "keyword-spacing": "error",
    "lines-around-comment": ["error", {
        "beforeBlockComment": true,
        "afterBlockComment": false,
        "beforeLineComment": true,
        "afterLineComment": false
    }],
    "new-cap": "error",
    "newline-after-var": ["error", "never"],
    "new-parens": "error",
    "no-array-constructor": "error",
    "no-invalid-this": "error",
    "no-multi-spaces": "error",
    "no-redeclare": "error",
    "no-return-assign": "error",
    "no-spaced-func": "error",
    "no-trailing-spaces": "error",
    "semi": "error",
    "semi-spacing": "error",
    "quotes":["error","double"],
    "space-before-function-paren": ["error", "never"],
    "space-in-parens": "error",
    "space-infix-ops": "error",
    "space-unary-ops": ["error", {"words": true, "nonwords": false}],
    "spaced-comment": "error",
    "yoda": ["error", "never"],
    "no-mixed-requires": "error",
    "handle-callback-err": ["error", "err"]
  }
}

六、配置文件说明

属性名	属性值	描述
[array-callback-return](http://eslint.org/docs/rules/array-callback-return)	"error"	Array执行回调函数返回语句
[indent](http://eslint.org/docs/rules/indent)	["error", 4, {"SwitchCase": 1}]	缩写格式的一致性
[block-spacing](http://eslint.org/docs/rules/block-spacing)	"error"	禁止执行空间内出现'-'
[brace-style](http://eslint.org/docs/rules/brace-style)	["error","1tbs"]	代码书写格式验证
[camelcase](http://eslint.org/docs/rules/camelcase)	["error", { "properties": "never" }]	属性命名规则可以不使用驼峰命名法
[callback-return](http://eslint.org/docs/rules/callback-return)	["error", ["cb", "callback", "next"]]	回调函数需要return进行返回
[comma-spacing](http://eslint.org/docs/rules/comma-spacing)	"error"	不允许在逗号前面出现空格
[comma-style](http://eslint.org/docs/rules/comma-style)	["error", "last"]	方数组元素、变量声明等直接需要逗号隔开
[consistent-return](http://eslint.org/docs/rules/consistent-return)	"error"	保持return返回的一致性
[curly](http://eslint.org/docs/rules/curly)	["error", "all"]	函数或者条件判断时需要统一使用大括号
[default-case](http://eslint.org/docs/rules/default-case)	"error"	switch语句中必须有default条件
[dot-notation](http://eslint.org/docs/rules/dot-notation)	["error", { "allowKeywords": false }]	不允许关键字出现在变量中
[eol-last](http://eslint.org/docs/rules/eol-last)	"error"	代码间间隔出现一行
[eqeqeq](http://eslint.org/docs/rules/eqeqeq)	"error"	消除不安全类型的全等操作
[guard-for-in](http://eslint.org/docs/rules/guard-for-in)	"error"	for循环中过滤掉一下不被需要的行为
[key-spacing](http://eslint.org/docs/rules/key-spacing)	["error", { "beforeColon": false, "afterColon": true }]	键和值前保留一个空格
[keyword-spacing](http://eslint.org/docs/rules/keyword-spacing)	"error"	确保字符前后空格的一致性
[lines-around-comment](http://eslint.org/docs/rules/lines-around-comment)	["error", { "beforeBlockComment": true, "afterBlockComment": false, "beforeLineComment": true, "afterLineComment": false }]	注释前需要空行，注释后不需要空行
[new-cap](http://eslint.org/docs/rules/new-cap)	"error"	构造函数首字母需要大写
[newline-after-var](http://eslint.org/docs/rules/newline-after-var)	["error", "never"]	var定义后不空行
[new-parens](http://eslint.org/docs/rules/new-parens)	"error"	没有参数时，构造函数也需要添加括号
[no-invalid-this](http://eslint.org/docs/rules/no-invalid-this)	"error"	不允许关键字this在函数或者类的外面
[no-multi-spaces](http://eslint.org/docs/rules/no-multi-spaces)	"error"	不允许键和值之间存在多个空格
[no-redeclare](http://eslint.org/docs/rules/no-redeclare)	"error"	不允许重复声明
[no-return-assign](http://eslint.org/docs/rules/no-return-assign)	"error"	不允许在return语句中任务
[no-spaced-func](http://eslint.org/docs/rules/no-spaced-func)	"error"	调用函数时，函数名和括号之间不能有空格。
[no-trailing-spaces](http://eslint.org/docs/rules/no-trailing-spaces)	"error"	不允许在语句后存在多余的空格
[semi](http://eslint.org/docs/rules/semi)	"error"	语句以分号结尾
[semi-spacing](http://eslint.org/docs/rules/semi-spacing)	"error"	分号前后不能有空格
[quotes](http://eslint.org/docs/rules/quotes)	["error","double"]	使用双引号
[space-before-function-paren](http://eslint.org/docs/rules/space-before-function-paren）	"space-before-function-paren": ["error", "never"]	不允许函数括号之间存在空格
[space-in-parens](http://eslint.org/docs/rules/space-in-parens)	"error"	不允许在括号里面存在空格
[space-infix-ops](http://eslint.org/docs/rules/space-infix-ops)	"error"	插入符合变量之间需要添加一个空格
[space-unary-ops](http://eslint.org/docs/rules/space-unary-ops)	["error", {"words": true, "nonwords": false}]	允许一元运算符操作
[spaced-comment](http://eslint.org/docs/rules/spaced-comment)	"error"	注释前需要一个空格
[yoda](http://eslint.org/docs/rules/yoda)	["error", "never"]	条件语句中，变量在赋值语句的前面
[no-mixed-requires](http://eslint.org/docs/rules/no-mixed-requires)	"error"	不允许混合requires文件
[no-new-require](http://eslint.org/docs/rules/no-new-require)	"error"	不允许new require出现
[no-path-concat](http://eslint.org/docs/rules/no-path-concat)	"error"	不允许路径以_链接
[handle-callback-err](http://eslint.org/docs/rules/handle-callback-err)	["error", "err"]	处理错误的回调函数