Jsx Key - Denoland — ContextQMD

Ensure the key attribute is present when passing iterables into JSX. It allows frameworks to optimize checking the order of elements.

Invalid:

tsx

const foo = [<div>foo</div>];
const foo = [<>foo</>];
[1, 2, 3].map(() => <div />);
Array.from([1, 2, 3], () => <div />);

Valid:

tsx

const foo = [<div key="a">foo</div>];
const foo = [<Fragment key="b">foo</Fragment>];
[1, 2, 3].map((x) => <div key={x} />);
Array.from([1, 2, 3], (x) => <div key={x} />);