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no-inferrable-types

Disallow explicit type declarations for variables or parameters initialized to a number, string, or boolean.

🎨

在 ESLint 配置 中扩展"plugin:@typescript-eslint/stylistic" 可启用此规则。

🔧

此规则报告的一些问题可通过 --fix ESLint 命令行选项自动修复。


TypeScript 能够根据参数、属性和变量的默认值或初始值推断其类型。 无需在初始化为布尔值、数字或字符串的这些构造之一上使用显式 : 类型注释。 这样做会给代码增加不必要的冗长 - 使其更难以阅读 - 并且在某些情况下可能会阻止 TypeScript 推断更具体的字面量类型（例如 10）而不是更一般的原始类型（例如 number）

英：TypeScript is able to infer the types of parameters, properties, and variables from their default or initial values. There is no need to use an explicit : type annotation on one of those constructs initialized to a boolean, number, or string. Doing so adds unnecessary verbosity to code -making it harder to read- and in some cases can prevent TypeScript from inferring a more specific literal type (e.g. 10) instead of the more general primitive type (e.g. number)

.eslintrc.cjs
module.exports = {
  "rules": {
    "@typescript-eslint/no-inferrable-types": "error"
  }
};
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示例​

const a: bigint = 10n;
const a: bigint = BigInt(10);
const a: boolean = !0;
const a: boolean = Boolean(null);
const a: boolean = true;
const a: null = null;
const a: number = 10;
const a: number = Infinity;
const a: number = NaN;
const a: number = Number('1');
const a: RegExp = /a/;
const a: RegExp = new RegExp('a');
const a: string = `str`;
const a: string = String(1);
const a: symbol = Symbol('a');
const a: undefined = undefined;
const a: undefined = void someValue;

class Foo {
  prop: number = 5;
}

function fn(a: number = 5, b: boolean = true) {}
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选项​

ignoreParameters​

当设置为 true 时，以下模式被视为有效：

英：When set to true, the following pattern is considered valid:

function foo(a: number = 5, b: boolean = true) {
  // ...
}
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ignoreProperties​

当设置为 true 时，以下模式被视为有效：

英：When set to true, the following pattern is considered valid:

class Foo {
  prop: number = 5;
}
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何时不使用它​

如果你强烈喜欢使用显式类型，无论是否可以推断它们，则此规则可能不适合你。

英：If you strongly prefer to have explicit types regardless of whether they can be inferred, this rule may not be for you.

进一步阅读​

选项​

该规则接受以下选项

type Options = [
  {
    ignoreParameters?: boolean;
    ignoreProperties?: boolean;
  },
];

const defaultOptions: Options = [
  { ignoreParameters: false, ignoreProperties: false },
];

资源​