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no-use-before-define

Disallow the use of variables before they are defined.


此规则扩展了基本 eslint/no-use-before-define 规则。 它增加了对 type、interface 和 enum 声明的支持。

英：This rule extends the base eslint/no-use-before-define rule. It adds support for type, interface and enum declarations.

选项​

该规则添加了以下选项：

英：This rule adds the following options:

interface Options extends BaseNoUseBeforeDefineOptions {
  enums?: boolean;
  typedefs?: boolean;
  ignoreTypeReferences?: boolean;
}

const defaultOptions: Options = {
  ...baseNoUseBeforeDefineDefaultOptions,
  enums: true,
  typedefs: true,
  ignoreTypeReferences: true,
};

enums​

如果这是 true，则此规则会在枚举声明之前对每个对枚举的引用触发警告。 如果这是 false，则当引用位于子作用域中时，此规则将忽略对枚举的引用。

英：If this is true, this rule warns every reference to a enum before the enum declaration. If this is false, this rule will ignore references to enums, when the reference is in a child scope.

{ "enums": true } 选项的代码示例：

英：Examples of code for the { "enums": true } option:

const x = Foo.FOO;

enum Foo {
  FOO,
}
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typedefs​

如果这是 true，则此规则会在类型声明之前对每个类型的引用触发警告。 如果这是 false，则此规则将忽略对类型的引用。

英：If this is true, this rule warns every reference to a type before the type declaration. If this is false, this rule will ignore references to types.

{ "typedefs": false } 选项的 correct 代码示例：

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

let myVar: StringOrNumber;
type StringOrNumber = string | number;
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ignoreTypeReferences​

如果这是 true，则此规则将忽略所有类型引用，例如类型注释和断言中的类型引用。 如果这是 false，这将检查所有类型引用。

英：If this is true, this rule ignores all type references, such as in type annotations and assertions. If this is false, this will will check all type references.

{ "ignoreTypeReferences": true } 选项的 correct 代码示例：

英：Examples of correct code for the { "ignoreTypeReferences": true } option:

let var1: StringOrNumber;
type StringOrNumber = string | number;

let var2: Enum;
enum Enum {}
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如何使用​

.eslintrc.cjs
module.exports = {
  "rules": {
    // Note: you must disable the base rule as it can report incorrect errors
    "no-use-before-define": "off",
    "@typescript-eslint/no-use-before-define": "error"
  }
};
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选项​

参见 eslint/no-use-before-define 选项。

资源​

摘自 ❤️ ESLint 内核