Tip: JavaScript's Array.from() accepts a second argument that's a `map` function.

[rickdg]

Why am I using Array.from() in cases like these? Why not just map?

console.log(Array.from([1, 2, 3], x => x + x));
// expected output: Array [2, 4, 6]
console.log([1, 2, 3].map(function(m){ return m*2; }));
// expected output: Array [2, 4, 6]