noUselessCatch

Diagnostic Category: lint/complexity/noUselessCatch

JavaScript (and super languages)

Since: v1.0.0

Sources:

Same as: no-useless-catch

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

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

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

  ✖ 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.

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

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

  ✖ 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

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

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

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

How to configure

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