arrayFilteredFinds

Reports using .filter() when only the first or last matching element is needed.

✅ This rule is included in the ts logical presets.

Using .filter() to get only the first or last matching element creates an unnecessary intermediate array. The .find() method is more efficient as it stops iteration once a match is found. Similarly, .findLast() is more efficient for finding the last matching element.

This rule reports:

• .filter()[0] or .filter().shift() or .filter().at(0) → prefer .find()
• .filter().pop() or .filter().at(-1) → prefer .findLast()

Examples

❌ Incorrect

declare const array: number[];
array.filter((value) => value > 0)[0];

declare const array: number[];
array.filter((value) => value > 0).shift();

declare const array: number[];
array.filter((value) => value > 0).at(0);

declare const array: number[];
array.filter((value) => value > 0).pop();

declare const array: number[];
array.filter((value) => value > 0).at(-1);

✅ Correct

declare const array: number[];
array.find((value) => value > 0);

declare const array: number[];
array.findLast((value) => value > 0);

declare const array: number[];
const filtered = array.filter((value) => value > 0);

declare const array: number[];
array.filter((value) => value > 0).length;

Options

This rule is not configurable.

When Not To Use It

If you need the full filtered array for other purposes beyond accessing the first element, you can disable this rule. However, in most cases where only the first match is needed, .find() is the better choice.

Further Reading

• MDN: Array.prototype.find()
• MDN: Array.prototype.findLast()
• MDN: Array.prototype.filter()

Equivalents in Other Linters

• ESLint: unicorn/prefer-array-find
• Oxlint: unicorn/prefer-array-find