prefer-array-slice.md

prefer-array-slice

📝 Prefer Array#slice() over Array#splice() when reading from the returned array.

💼🚫 This rule is enabled in the ✅ recommended config. This rule is disabled in the ☑️ unopinionated config.

💡 This rule is manually fixable by editor suggestions.

Prefer Array#slice() over Array#splice() when reading from the returned array.

Array#splice() mutates the source array. When the returned elements are immediately indexed or read with .at(), Array#slice() expresses the read-only intent without changing the source array.

Examples

// ❌
const foo = process.argv.splice(2)[0];

// ✅
const foo = process.argv.slice(2)[0];

// ❌
const foo = array.splice(index).at(0);

// ✅
const foo = array.slice(index).at(0);

// ✅
array.splice(index);

// ✅
array.splice(index, deleteCount)[0];

Keep Array#splice() when intentional mutation is part of the operation.