التحويل والفرد بإستخدام flatMap

const lines = ["Learn HTML", "Learn CSS"];
console.log(JSON.stringify(lines.flatMap(line => line.split(" "))));

["Learn","HTML","Learn","CSS"]

const numbers = [1, 2, 3];
console.log(JSON.stringify(numbers.flatMap(n => n > 1 ? [n, n * 10] : [])));

[2,20,3,30]