no-unnecessary-boolean-literal-compare

Disallow unnecessary equality comparisons against boolean literals.

🔒

在 ESLint 配置 中扩展"plugin:@typescript-eslint/strict-type-checked" 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。

💭

该规则需要 类型信息 才能运行，但这会带来性能方面的权衡。

没有必要将布尔值与布尔字面量进行比较：这些比较会产生相同的布尔值。直接使用布尔值或通过一元否定（!value）更简洁明了。

¥Comparing boolean values to boolean literals is unnecessary: those comparisons result in the same booleans. Using the boolean values directly, or via a unary negation (!value), is more concise and clearer.

此规则可确保你不会包含与布尔字面量不必要的比较。如果比较仅针对具有 boolean 类型的任何变量检查布尔文字，则认为比较是不必要的。如果类型是布尔值的联合（string | boolean、SomeObject | boolean 等），则不认为比较是不必要的。

¥This rule ensures that you do not include unnecessary comparisons with boolean literals. A comparison is considered unnecessary if it checks a boolean literal against any variable with just the boolean type. A comparison is not considered unnecessary if the type is a union of booleans (string | boolean, SomeObject | boolean, etc.).

Flat Config

eslint.config.mjs

export default tseslint.config({
  rules: {
    "@typescript-eslint/no-unnecessary-boolean-literal-compare": "error"
  }
});

Legacy Config

.eslintrc.cjs

module.exports = {
  "rules": {
    "@typescript-eslint/no-unnecessary-boolean-literal-compare": "error"
  }
};

在线运行试试这个规则 ↗

示例

¥Examples

注意

在整个页面中，示例中仅使用严格相等（=== 和 !==）。然而，该规则的实现并不区分严格平等和松散平等。如果使用 ==，下面任何使用 === 的示例都将以相同的方式处理，如果使用 !=，!== 也将以相同的方式处理。

¥Throughout this page, only strict equality (=== and !==) are used in the examples. However, the implementation of the rule does not distinguish between strict and loose equality. Any example below that uses === would be treated the same way if == was used, and !== would be treated the same way if != was used.

❌ Incorrect

declare const someCondition: boolean;
if (someCondition === true) {
}

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✅ Correct

declare const someCondition: boolean;
if (someCondition) {
}

declare const someObjectBoolean: boolean | Record<string, unknown>;
if (someObjectBoolean === true) {
}

declare const someStringBoolean: boolean | string;
if (someStringBoolean === true) {
}

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选项

该规则接受以下选项:

type Options = [
  {
    /** Whether to allow comparisons between nullable boolean variables and `false`. */
    allowComparingNullableBooleansToFalse?: boolean;
    /** Whether to allow comparisons between nullable boolean variables and `true`. */
    allowComparingNullableBooleansToTrue?: boolean;
    /** Unless this is set to `true`, the rule will error on every file whose `tsconfig.json` does _not_ have the `strictNullChecks` compiler option (or `strict`) set to `true`. */
    allowRuleToRunWithoutStrictNullChecksIKnowWhatIAmDoing?: boolean;
  },
];

const defaultOptions: Options = [
  {
    allowComparingNullableBooleansToFalse: true,
    allowComparingNullableBooleansToTrue: true,
    allowRuleToRunWithoutStrictNullChecksIKnowWhatIAmDoing: false,
  },
];

¥Options

此规则始终检查布尔变量和布尔字面量之间的比较。默认情况下不检查可空布尔变量和布尔文字之间的比较。

¥This rule always checks comparisons between a boolean variable and a boolean literal. Comparisons between nullable boolean variables and boolean literals are not checked by default.

allowComparingNullableBooleansToTrue

Whether to allow comparisons between nullable boolean variables and true. Default: true.

带有 { allowComparingNullableBooleansToTrue: false } 的此规则的代码示例：

¥Examples of code for this rule with { allowComparingNullableBooleansToTrue: false }:

❌ Incorrect

declare const someUndefinedCondition: boolean | undefined;
if (someUndefinedCondition === true) {
}

declare const someNullCondition: boolean | null;
if (someNullCondition !== true) {
}

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✅ Correct

declare const someUndefinedCondition: boolean | undefined;
if (someUndefinedCondition) {
}

declare const someNullCondition: boolean | null;
if (!someNullCondition) {
}

Open in Playground

allowComparingNullableBooleansToFalse

Whether to allow comparisons between nullable boolean variables and false. Default: true.

带有 { allowComparingNullableBooleansToFalse: false } 的此规则的代码示例：

¥Examples of code for this rule with { allowComparingNullableBooleansToFalse: false }:

❌ Incorrect

declare const someUndefinedCondition: boolean | undefined;
if (someUndefinedCondition === false) {
}

declare const someNullCondition: boolean | null;
if (someNullCondition !== false) {
}

Open in Playground

✅ Correct

declare const someUndefinedCondition: boolean | undefined;
if (!(someUndefinedCondition ?? true)) {
}

declare const someNullCondition: boolean | null;
if (someNullCondition ?? true) {
}

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allowRuleToRunWithoutStrictNullChecksIKnowWhatIAmDoing

已弃用

此选项将在下一个主要版本的 typescript-eslint 中删除。

¥This option will be removed in the next major version of typescript-eslint.

Unless this is set to true, the rule will error on every file whose tsconfig.json does not have the strictNullChecks compiler option (or strict) set to true. Default: false.

如果没有 strictNullChecks，TypeScript 基本上会从类型中删除 undefined 和 null。这意味着当此规则检查变量的类型时，它将无法判断变量可能是 null 还是 undefined，这实际上使此规则毫无用处。

¥Without strictNullChecks, TypeScript essentially erases undefined and null from the types. This means when this rule inspects the types from a variable, it will not be able to tell that the variable might be null or undefined, which essentially makes this rule useless.

你应该使用 strictNullChecks 来确保代码库中的完全类型安全。

¥You should be using strictNullChecks to ensure complete type-safety in your codebase.

如果由于某种原因你无法打开 strictNullChecks，但仍想使用此规则 - 你可以使用此选项来允许它 - 但要知道，如果关闭编译器选项，此规则的行为是未定义的。如果你使用此选项，我们将不接受错误报告。

¥If for some reason you cannot turn on strictNullChecks, but still want to use this rule - you can use this option to allow it - but know that the behavior of this rule is undefined with the compiler option turned off. We will not accept bug reports if you are using this option.

修复器

¥Fixer

比较	定影器输出	注意
booleanVar === true	booleanVar
booleanVar !== true	!booleanVar
booleanVar === false	!booleanVar
booleanVar !== false	booleanVar
nullableBooleanVar === true	nullableBooleanVar	仅当 allowComparingNullableBooleansToTrue 选项为 false 时才检查/修复
nullableBooleanVar !== true	!nullableBooleanVar	仅当 allowComparingNullableBooleansToTrue 选项为 false 时才检查/修复
nullableBooleanVar === false	!(nullableBooleanVar ?? true)	仅当 allowComparingNullableBooleansToFalse 选项为 false 时才检查/修复
nullableBooleanVar !== false	nullableBooleanVar ?? true	仅当 allowComparingNullableBooleansToFalse 选项为 false 时才检查/修复

何时不使用它

¥When Not To Use It

禁用 strictNullChecks 时请勿使用此规则。ESLint 无法区分 false 和 undefined 或 null 值。使用自动修复时，这可能会导致意外的代码更改。

¥Do not use this rule when strictNullChecks is disabled. ESLint is not able to distinguish between false and undefined or null values. This can cause unintended code changes when using autofix.

---

Type checked lint rules are more powerful than traditional lint rules, but also require configuring type checked linting.

See Troubleshooting > Linting with Type Information > Performance if you experience performance degradations after enabling type checked rules.

'## 资源'

• 规则源码
• 测试源码