noUselessCatch (JavaScript)

Language JavaScript (and super languages)

Summary

Rule available since: v1.0.0
Diagnostic Category: lint/complexity/noUselessCatch
This rule is recommended, meaning it is enabled by default.
This rule has an unsafe fix.
The default severity of this rule is information.
Sources:
- Same as no-useless-catch

How to configure

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{
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  "linter": {
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    "rules": {
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      "complexity": {
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        "noUselessCatch": "error"
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      }
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    }
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  }
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}

Description

Disallow unnecessary catch clauses.

A catch clause that only rethrows the original error is redundant, and has no effect on the runtime behavior of the program. These redundant clauses can be a source of confusion and code bloat, so it’s better to disallow these unnecessary catch clauses.

Examples

Invalid

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try {
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    doSomething();
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} catch(e) {
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    throw e;
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}

code-block.js:4:5 lint/complexity/noUselessCatch ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ The catch clause that only rethrows the original error is useless.
  
    2 │     doSomething();
    3 │ } catch(e) {
  > 4 │     throw e;
      │     ^^^^^^^^
    5 │ }
    6 │ 
  
  ℹ An unnecessary catch clause can be confusing.

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try {
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    doSomething();
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} catch(e) {
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    throw e;
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} finally {
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    doCleanUp();
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}

code-block.js:4:5 lint/complexity/noUselessCatch  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ The catch clause that only rethrows the original error is useless.
  
    2 │     doSomething();
    3 │ } catch(e) {
  > 4 │     throw e;
      │     ^^^^^^^^
    5 │ } finally {
    6 │     doCleanUp();
  
  ℹ An unnecessary catch clause can be confusing.
  
  ℹ Unsafe fix: Remove the catch clause.
  
    1 1 │   try {
    2 2 │       doSomething();
    3   │ - }·catch(e)·{
    4   │ - ····throw·e;
    5   │ - }·finally·{
      3 │ + }·finally·{
    6 4 │       doCleanUp();
    7 5 │   }

Valid

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try {
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    doSomething();
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} catch(e) {
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    doSomethingWhenCatch();
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    throw e;
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}

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try {
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    doSomething();
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} catch(e) {
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    handleError(e);
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}

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try {
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    doSomething();
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} finally {
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    doCleanUp();
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}