非常教程

Eslint参考手册

规则 | Rules

global-require

在 Node.js 中,使用该require()函数包含模块依赖关系,例如:

var fs = require("fs");

尽管require()可以在代码中的任何地方调用,但某些样式指南规定应该仅在模块的顶层调用它,以便更容易地识别依赖关系。例如,当它们深深嵌套在函数和其他语句中时,很难确定依赖关系:

function foo() {

    if (condition) {
        var fs = require("fs");
    }
}

由于require()做了同步加载,因此在其他位置使用时可能会导致性能问题。

此外,ES6 模块强制要求importexport声明只能出现在模块主体的顶层。

规则细节

此规则要求所有调用require()都位于模块的顶层,类似于 ES6 importexport语句,这也只能在顶层发生。

此规则的错误代码示例:

/*eslint global-require: "error"*/
/*eslint-env es6*/

// calling require() inside of a function is not allowed
function readFile(filename, callback) {
    var fs = require('fs');
    fs.readFile(filename, callback)
}

// conditional requires like this are also not allowed
if (DEBUG) { require('debug'); }

// a require() in a switch statement is also flagged
switch(x) { case '1': require('1'); break; }

// you may not require() inside an arrow function body
var getModule = (name) => require(name);

// you may not require() inside of a function body as well
function getModule(name) { return require(name); }

// you may not require() inside of a try/catch block
try {
    require(unsafeModule);
} catch(e) {
    console.log(e);
}

此规则的正确代码示例:

/*eslint global-require: "error"*/

// all these variations of require() are ok
require('x');
var y = require('y');
var z;
z = require('z').initialize();

// requiring a module and using it in a function is ok
var fs = require('fs');
function readFile(filename, callback) {
    fs.readFile(filename, callback)
}

// you can use a ternary to determine which module to require
var logger = DEBUG ? require('dev-logger') : require('logger');

// if you want you can require() at the end of your module
function doSomethingA() {}
function doSomethingB() {}
var x = require("x"),
    z = require("z");

何时不使用它

如果您有一个必须使用来自文件系统的信息进行初始化的模块,或者仅在非常罕见的情况下使用模块,并且会导致大量的加载开销,那么禁用该规则可能是有意义的。如果你需要require()一个内部的可选依赖try/ catch,您可以只使用这种依赖性禁用该规则// eslint-disable-line global-require评论。

版本

该规则在 ESLint 1.4.0 中引入。

资源

  • Rule source
  • Documentation source

规则 | Rules相关

1.accessor-pairs
2.array-bracket-newline
3.array-bracket-spacing
4.array-callback-return
5.array-element-newline
6.arrow-body-style
7.arrow-parens
8.arrow-spacing
9.block-scoped-var
10.block-spacing
11.brace-style
12.callback-return
13.camelcase
14.capitalized-comments
15.class-methods-use-this
16.comma-dangle
17.comma-spacing
18.comma-style
19.complexity
20.computed-property-spacing
21.consistent-return
22.consistent-this
23.constructor-super
24.curly
25.default-case
26.dot-location
27.dot-notation
28.eol-last
29.eqeqeq
30.for-direction
31.func-call-spacing
32.func-name-matching
33.func-names
34.func-style
35.function-paren-newline
36.generator-star
37.generator-star-spacing
38.getter-return
39.global-strict
40.guard-for-in
41.handle-callback-err
42.id-blacklist
43.id-length
44.id-match
45.implicit-arrow-linebreak
46.indent
47.indent-legacy
48.init-declarations
49.jsx-quotes
50.key-spacing
51.keyword-spacing
52.line-comment-position
53.linebreak-style
54.lines-around-comment
55.lines-around-directive
56.lines-between-class-members
57.max-depth
58.max-len
59.max-lines
60.max-nested-callbacks
61.max-params
62.max-statements
63.max-statements-per-line
64.multiline-comment-style
65.multiline-ternary
66.new-cap
67.new-parens
68.newline-after-var
69.newline-before-return
70.newline-per-chained-call
71.no-alert
72.no-array-constructor
73.no-arrow-condition
74.no-await-in-loop
75.no-bitwise
76.no-buffer-constructor
77.no-caller
78.no-case-declarations
79.no-catch-shadow
80.no-class-assign
81.no-comma-dangle
82.no-compare-neg-zero
83.no-cond-assign
84.no-confusing-arrow
85.no-console
86.no-const-assign
87.no-constant-condition
88.no-continue
89.no-control-regex
90.no-debugger
91.no-delete-var
92.no-div-regex
93.no-dupe-args
94.no-dupe-class-members
95.no-dupe-keys
96.no-duplicate-case
97.no-duplicate-imports
98.no-else-return
99.no-empty
100.no-empty-character-class
Eslint

ESLint 是一个代码规范和错误检查工具,有以下几个特性。所有东西都是可以插拔的。你可以调用任意的 rule api 或者 formatter api 去打包或者定义 rule or formatter。任意的 rule 都是独立的。没有特定的 coding style,你可以自己配置。

主页 https://eslint.org/
源码 https://github.com/eslint/eslint
发布版本 4.12.0

Eslint目录

1.指南 | Guide
2.规则 | Rules