Require Dot Notation (dot-notation)

要求使用点号 (dot-notation)

The --fix option on the command line can automatically fix some of the problems reported by this rule.

命令行中的 --fix 选项可以自动修复一些该规则报告的问题。

In JavaScript, one can access properties using the dot notation (foo.bar) or square-bracket notation (foo["bar"]). However, the dot notation is often preferred because it is easier to read, less verbose, and works better with aggressive JavaScript minimizers.

在 JavaScript 中，你可以使用点号 (foo.bar) 或者方括号 (foo["bar"])来访问属性。然而，点号通常是首选，因为它更加易读，简洁，也更适于 JavaScript 压缩。

foo["bar"];

Rule Details

This rule is aimed at maintaining code consistency and improving code readability by encouraging use of the dot notation style whenever possible. As such, it will warn when it encounters an unnecessary use of square-bracket notation.

该规则旨在维护代码的一致性，通过鼓励使用点号操作符来提高代码可读性。因此，当遇到不必要的方括号时，该规则将发出警告。

Examples of incorrect code for this rule:

错误代码示例：

/*eslint dot-notation: "error"*/

var x = foo["bar"];

Examples of correct code for this rule:

正确代码示例：

/*eslint dot-notation: "error"*/

var x = foo.bar;

var x = foo[bar];    // Property name is a variable, square-bracket notation required

Options

This rule accepts a single options argument:

该规则接受单个选项参数：

Set the allowKeywords option to false (default is true) to follow ECMAScript version 3 compatible style, avoiding dot notation for reserved word properties.
为了兼容 ECMAScript 3，设置 allowKeywords 为 false（默认为true），避免对是保留字的属性使用点号。
Set the allowPattern option to a regular expression string to allow bracket notation for property names that match a pattern (by default, no pattern is tested).
将 allowPattern设置为一个正则表达式字符串允许匹配这个模式的属性名使用括号。（默认情况下,没有匹配模式）。

allowKeywords

Examples of correct code for the { "allowKeywords": false } option:

选项 { "allowKeywords": false } 的正确代码示例：

/*eslint dot-notation: ["error", { "allowKeywords": false }]*/

var foo = { "class": "CS 101" }
var x = foo["class"]; // Property name is a reserved word, square-bracket notation required

allowPattern

For example, when preparing data to be sent to an external API, it is often required to use property names that include underscores. If the camelcase rule is in effect, these snake case properties would not be allowed. By providing an allowPattern to the dot-notation rule, these snake case properties can be accessed with bracket notation.

例如，当把准备好的数据发送到外部接口时，经常要求使用包括下划线的属性名。如果启用了 camelcase 规则，这些 snake case 属性将不被允许使用。通过给 dot-notation 规则提供 allowPattern 选项，这些属性就可以使用括号来访问了。

Examples of correct code for the sample { "allowPattern": "^[a-z]+(_[a-z]+)+$" } option:

选项 { "allowPattern": "^[a-z]+(_[a-z]+)+$" } 的正确代码示例：

/*eslint camelcase: "error"*/
/*eslint dot-notation: ["error", { "allowPattern": "^[a-z]+(_[a-z]+)+$" }]*/

var data = {};
data.foo_bar = 42;

var data = {};
data["fooBar"] = 42;

var data = {};
data["foo_bar"] = 42; // no warning

Version

This rule was introduced in ESLint 0.0.7.

该规则在 ESLint 0.0.7 中被引入