useFind

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JavaScript (and super languages)

Summary

Diagnostic Category: lint/nursery/useFind
This rule doesn’t have a fix.
The default severity of this rule is information.
This rule belongs to the following domains:
- project
Sources:
- Same as @typescript-eslint/prefer-find

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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        "useFind": "error"
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      }
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    }
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  }
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}

Description

Enforce the use of Array.prototype.find() over Array.prototype.filter() followed by [0] when looking for a single result.

When searching for the first item in an array matching a condition, it may be tempting to use code like arr.filter(x => x > 0)[0]. However, it is simpler to use Array.prototype.find() instead, arr.find(x => x > 0), which also returns the first entry matching a condition. Because the .find() only needs to execute the callback until it finds a match, it’s also more efficient.

Examples

Invalid

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[1, 2, 3].filter(x => x > 1)[0];

/invalid.ts:1:1 lint/nursery/useFind ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ Prefer using Array#find() over Array#filter[0].
  
  > 1 │ [1, 2, 3].filter(x => x > 1)[0];
      │ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    2 │ 
  
  ℹ Use Array#find() instead of Array#filter[0] to improve readability.

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[1, 2, 3].filter(x => x > 1).at(0);

/invalid2.ts:1:1 lint/nursery/useFind ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ Prefer using Array#find() over Array#filter[0].
  
  > 1 │ [1, 2, 3].filter(x => x > 1).at(0);
      │ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    2 │ 
  
  ℹ Use Array#find() instead of Array#filter[0] to improve readability.

Valid

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[1, 2, 3].find(x => x > 1);