noNonNullAssertion

TypeScript and TSX

摘要

¥Summary

规则生效日期：v1.0.0

¥Rule available since: v1.0.0
诊断类别：lint/style/noNonNullAssertion

¥Diagnostic Category: lint/style/noNonNullAssertion
此规则为推荐规则，默认启用。

¥This rule is recommended, which means is enabled by default.
此规则包含 unsafe 修复程序。

¥This rule has an unsafe fix.
此规则的默认严重级别为 warning。

¥The default severity of this rule is warning.
来源：

¥Sources:
- 与 @typescript-eslint/no-non-null-assertion 相同
  
  ¥Same as @typescript-eslint/no-non-null-assertion

如何配置

¥How to configure

1
{
2
  "linter": {
3
    "rules": {
4
      "style": {
5
        "noNonNullAssertion": "error"
6
      }
7
    }
8
  }
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}

描述

¥Description

禁止使用 ! 后缀运算符进行非空断言。

¥Disallow non-null assertions using the ! postfix operator.

TypeScript 的 ! 非空断言运算符向类型系统断言表达式不可为空，如 not null 或 undefined。使用断言告诉类型系统新信息通常表明代码不是完全类型安全的。通常最好构造程序逻辑，以便 TypeScript 了解值何时可以为空。

¥TypeScript’s ! non-null assertion operator asserts to the type system that an expression is non-nullable, as in not null or undefined. Using assertions to tell the type system new information is often a sign that code is not fully type-safe. It’s generally better to structure program logic so that TypeScript understands when values may be nullable.

示例

¥Examples

无效

¥Invalid

1
interface Example {
2
  property?: string;
3
}
4
declare const foo: Example;
5
const includesBaz = foo.property!.includes('baz');

code-block.ts:5:21 lint/style/noNonNullAssertion  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ Forbidden non-null assertion.
  
    3 │ }
    4 │ declare const foo: Example;
  > 5 │ const includesBaz = foo.property!.includes(‘baz’);
      │                     ^^^^^^^^^^^^^
    6 │ 
  
  ℹ Unsafe fix: Replace with optional chain operator ?. This operator includes runtime checks, so it is safer than the compile-only non-null assertion operator
  
    3 3 │   }
    4 4 │   declare const foo: Example;
    5   │ - const·includesBaz·=·foo.property!.includes(‘baz’);
      5 │ + const·includesBaz·=·foo.property?.includes(‘baz’);
    6 6 │

1
(b!! as number) = "test";

code-block.ts:1:2 lint/style/noNonNullAssertion ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ Forbidden non-null assertion.
  
  > 1 │ (b!! as number) = “test”;
      │  ^^^
    2 │

有效

¥Valid

1
interface Example {
2
  property?: string;
3
}
4

5
declare const foo: Example;
6
const includesBaz = foo.property?.includes('baz') ?? false;

noNonNullAssertion

摘要

如何配置

描述

示例

无效

有效

相关链接