arrayUnnecessaryLengthChecks

Reports unnecessary array length checks before .some() or .every() calls.

✅ This rule is included in the ts logical preset.

Array#some() returns false for an empty array, so checking array.length !== 0 or array.length > 0 before calling .some() is redundant.

Array#every() returns true for an empty array, so checking array.length === 0 before calling .every() is redundant.

This rule reports these unnecessary length checks.

Examples

❌ Incorrect

declare const array: boolean[];
array.length !== 0 && array.some(Boolean);

declare const array: boolean[];
array.length > 0 && array.some(Boolean);

declare const array: boolean[];
array.length === 0 || array.every(Boolean);

✅ Correct

declare const array: boolean[];
array.some(Boolean);

declare const array: boolean[];
array.every(Boolean);

declare const array: boolean[];
array.length !== 0 && array.every(Boolean);

declare const array: boolean[];
array.length === 0 || array.some(Boolean);

Options

This rule is not configurable.

When Not To Use It

If you prefer explicit length checks for documentation purposes, or if your team’s coding standards require them, you may disable this rule.

Further Reading

• MDN: Array.prototype.some()
• MDN: Array.prototype.every()

Equivalents in Other Linters

• ESLint: unicorn/no-useless-length-check
• Oxlint: unicorn/no-useless-length-check