noUselessCatchBinding

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JavaScript (and super languages)

Summary

Rule available since: v2.2.3
Diagnostic Category: lint/nursery/noUselessCatchBinding
This rule has an unsafe fix.
The default severity of this rule is information.

How to configure

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{
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  "linter": {
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    "rules": {
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      "nursery": {
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        "noUselessCatchBinding": "error"
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      }
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    }
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  }
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}

Description

Disallow unused catch bindings.

This rule disallows unnecessary catch bindings in accordance with ECMAScript 2019. See also: the ECMAScript 2019 “optional catch binding” feature in the language specification.

Examples

Invalid

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try {
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    // Do something
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} catch (unused) {}

code-block.js:3:9 lint/nursery/noUselessCatchBinding  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ This catch binding is unused.
  
    1 │ try {
    2 │     // Do something
  > 3 │ } catch (unused) {}
      │         ^^^^^^^^
    4 │ 
  
  ℹ Since ECMAScript 2019, catch bindings are optional; you can omit the catch binding if you don’t need it.
  
  ℹ This rule belongs to the nursery group, which means it is not yet stable and may change in the future. Visit https://biomejs.dev/linter/#nursery for more information.
  
  ℹ Unsafe fix: Remove the catch binding.
  
    3 │ }·catch·(unused)·{}
      │         ---------

1
try {
2
    // Do something
3
} catch ({ unused }) {}

code-block.js:3:9 lint/nursery/noUselessCatchBinding  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ This catch binding is unused.
  
    1 │ try {
    2 │     // Do something
  > 3 │ } catch ({ unused }) {}
      │         ^^^^^^^^^^^^
    4 │ 
  
  ℹ Since ECMAScript 2019, catch bindings are optional; you can omit the catch binding if you don’t need it.
  
  ℹ This rule belongs to the nursery group, which means it is not yet stable and may change in the future. Visit https://biomejs.dev/linter/#nursery for more information.
  
  ℹ Unsafe fix: Remove the catch binding.
  
    3 │ }·catch·({·unused·})·{}
      │         -------------

1
try {
2
    // Do something
3
} catch ({ unused1, unused2 }) {}

code-block.js:3:9 lint/nursery/noUselessCatchBinding  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ This catch binding is unused.
  
    1 │ try {
    2 │     // Do something
  > 3 │ } catch ({ unused1, unused2 }) {}
      │         ^^^^^^^^^^^^^^^^^^^^^^
    4 │ 
  
  ℹ Since ECMAScript 2019, catch bindings are optional; you can omit the catch binding if you don’t need it.
  
  ℹ This rule belongs to the nursery group, which means it is not yet stable and may change in the future. Visit https://biomejs.dev/linter/#nursery for more information.
  
  ℹ Unsafe fix: Remove the catch binding.
  
    3 │ }·catch·({·unused1,·unused2·})·{}
      │         -----------------------

Valid

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try {
2
    // Do something
3
} catch (used) {
4
    console.error(used);
5
}

1
try {
2
    // Do something
3
} catch ({ used }) {
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    console.error(used);
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}

1
try {
2
    // Do something
3
} catch ({ used, unused }) {
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    console.error(used);
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}

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try {
2
    // Do something
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} catch {}