prefer-negative-index

📝 Prefer negative index over .length - index when possible.

💼 This rule is enabled in the following configs: ✅ recommended, ☑️ unopinionated.

🔧 This rule is automatically fixable by the --fix CLI option.

Prefer negative index over calculating from .length for:

Examples

// ❌
foo.slice(foo.length - 2, foo.length - 1);

// ✅
foo.slice(-2, -1);

// ❌
foo.splice(foo.length - 1, 1);

// ✅
foo.splice(-1, 1);

// ❌
foo.at(foo.length - 1);

// ✅
foo.at(-1);

// ❌
Array.prototype.slice.call(foo, foo.length - 2, foo.length - 1);

// ✅
Array.prototype.slice.call(foo, -2, -1);

// ❌
Array.prototype.slice.apply(foo, [foo.length - 2, foo.length - 1]);

// ✅
Array.prototype.slice.apply(foo, [-2, -1]);