arrayFinds

Reports using .filter()[0] instead of .find() when looking for a single element.

✅ This rule is included in the ts stylistic preset.

When searching for the first item in an array matching a condition, using .filter(...)[0] is less efficient than using .find(...). The .find() method stops searching after finding the first match, whereas .filter() iterates through the entire array.

Examples

❌ Incorrect

const values = [1, 2, 3, 4, 5];
const first = values.filter((value) => value > 3)[0];

const users = [{ name: "Alice" }, { name: "Bob" }];
const user = users.filter((user) => user.name === "Alice")[0];

✅ Correct

const values = [1, 2, 3, 4, 5];
const first = values.find((value) => value > 3);

const users = [{ name: "Alice" }, { name: "Bob" }];
const user = users.find((user) => user.name === "Alice");

const values = [1, 2, 3, 4, 5];
const allPositive = values.filter((value) => value > 0);

Options

This rule is not configurable.

When Not To Use It

If you intentionally use .filter(...)[0] to execute side effects in the callback on all array elements before returning the first match, you may want to disable this rule. However, this pattern is unusual and may indicate a need for code refactoring.

Further Reading

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

Equivalents in Other Linters

• ESLint: @typescript-eslint/prefer-find