noSwitchDeclarations

JavaScript (and super languages)

摘要

¥Summary

规则生效日期：v1.0.0

¥Rule available since: v1.0.0
诊断类别：lint/correctness/noSwitchDeclarations

¥Diagnostic Category: lint/correctness/noSwitchDeclarations
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 safe 修复程序。

¥This rule has a safe fix.
此规则的默认严重级别为 error。

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

¥Sources:
- 与 no-case-declarations 相同
  
  ¥Same as no-case-declarations

如何配置

¥How to configure

1
{
2
  "linter": {
3
    "rules": {
4
      "correctness": {
5
        "noSwitchDeclarations": "error"
6
      }
7
    }
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  }
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}

描述

¥Description

禁止在 switch 子句中使用词汇声明。

¥Disallow lexical declarations in switch clauses.

switch 子句中的词汇声明可在整个 switch 中访问。但是，它仅在分配时才会初始化，这只有在到达定义它的 switch 子句时才会发生。

¥Lexical declarations in switch clauses are accessible in the entire switch. However, it only gets initialized when it is assigned, which will only happen if the switch clause where it is defined is reached.

要确保词汇声明仅适用于当前 switch 子句，请将声明封装在块中。

¥To ensure that the lexical declarations only apply to the current switch clause wrap your declarations in a block.

示例

¥Examples

无效

¥Invalid

1
switch (foo) {
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    case 0:
3
        const x = 1;
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        break;
5
    case 2:
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        x; // `x` can be used while it is not initialized
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        break;
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}

code-block.js:3:9 lint/correctness/noSwitchDeclarations  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Other switch clauses can erroneously access this declaration.
    Wrap the declaration in a block to restrict its access to the switch clause.
  
    1 │ switch (foo) {
    2 │     case 0:
  > 3 │         const x = 1;
      │         ^^^^^^^^^^^
    4 │         break;
    5 │     case 2:
  
  ℹ The declaration is defined in this switch clause:
  
    1 │ switch (foo) {
  > 2 │     case 0:
      │     ^^^^^^^
  > 3 │         const x = 1;
  > 4 │         break;
      │         ^^^^^^
    5 │     case 2:
    6 │         x; // `x` can be used while it is not initialized
  
  ℹ Safe fix: Wrap the declaration in a block.
  
    1  1 │   switch (foo) {
    2    │ - ····case·0:
       2 │ + ····case·0:·{
    3  3 │           const x = 1;
    4    │ - ········break;
       4 │ + ········break;
       5 │ + ····}
    5  6 │       case 2:
    6  7 │           x; // `x` can be used while it is not initialized

1
switch (foo) {
2
    case 0:
3
        function f() {}
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        break;
5
    case 2:
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        f(); // `f` can be called here
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        break;
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}

code-block.js:3:9 lint/correctness/noSwitchDeclarations  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Other switch clauses can erroneously access this declaration.
    Wrap the declaration in a block to restrict its access to the switch clause.
  
    1 │ switch (foo) {
    2 │     case 0:
  > 3 │         function f() {}
      │         ^^^^^^^^^^^^^^^
    4 │         break;
    5 │     case 2:
  
  ℹ The declaration is defined in this switch clause:
  
    1 │ switch (foo) {
  > 2 │     case 0:
      │     ^^^^^^^
  > 3 │         function f() {}
  > 4 │         break;
      │         ^^^^^^
    5 │     case 2:
    6 │         f(); // `f` can be called here
  
  ℹ Safe fix: Wrap the declaration in a block.
  
    1  1 │   switch (foo) {
    2    │ - ····case·0:
       2 │ + ····case·0:·{
    3  3 │           function f() {}
    4    │ - ········break;
       4 │ + ········break;
       5 │ + ····}
    5  6 │       case 2:
    6  7 │           f(); // `f` can be called here

1
switch (foo) {
2
    case 0:
3
        class A {}
4
        break;
5
    default:
6
        new A(); // `A` can be instantiated here
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        break;
8
}

code-block.js:3:9 lint/correctness/noSwitchDeclarations  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Other switch clauses can erroneously access this declaration.
    Wrap the declaration in a block to restrict its access to the switch clause.
  
    1 │ switch (foo) {
    2 │     case 0:
  > 3 │         class A {}
      │         ^^^^^^^^^^
    4 │         break;
    5 │     default:
  
  ℹ The declaration is defined in this switch clause:
  
    1 │ switch (foo) {
  > 2 │     case 0:
      │     ^^^^^^^
  > 3 │         class A {}
  > 4 │         break;
      │         ^^^^^^
    5 │     default:
    6 │         new A(); // `A` can be instantiated here
  
  ℹ Safe fix: Wrap the declaration in a block.
  
    1  1 │   switch (foo) {
    2    │ - ····case·0:
       2 │ + ····case·0:·{
    3  3 │           class A {}
    4    │ - ········break;
       4 │ + ········break;
       5 │ + ····}
    5  6 │       default:
    6  7 │           new A(); // `A` can be instantiated here

有效

¥Valid

1
switch (foo) {
2
    case 0: {
3
        const x = 1;
4
        break;
5
    }
6
    case 1:
7
        // `x` is not visible here
8
        break;
9
}

noSwitchDeclarations

摘要

如何配置

描述

示例

无效

有效

相关链接