2022・07・25

• generate an array of number:

Array(4).fill(['a','b']).flat()
// (8) ['a', 'b', 'a', 'b', 'a', 'b', 'a', 'b']

• this trick works with jsx too. useful for component mocking in storybook,.

const items = Array(100)
  .fill(<div>hello</div>)