no-useless-spread.md

Pattern: Unnecessary spread operator usage

Issue: -

Description

Many built-in methods and constructs (Map, Set, Promise.all, for...of, yield*) already accept iterables, making spread syntax unnecessary. Similarly, spreading array or object literals within their own literal type adds no value.

Examples

Example of incorrect code:

const array = [firstElement, ...[secondElement], thirdElement];
await Promise.all([...iterable]);
for (const foo of [...set]);
function* foo() {
  yield* [...anotherGenerator()];
}
function foo(bar) {
  return [...bar.map((x) => x * 2)];
}

Example of correct code:

const array = [firstElement, secondElement, thirdElement];
await Promise.all(iterable);
for (const foo of set);
function* foo() {
  yield* anotherGenerator();
}
function foo(bar) {
  return bar.map((x) => x * 2);
}