[JS] Array.from ( )

Array.from ( )

きほんけいじょう

Array.from(arrayLike[, mapFn[, thisArg]])

戻り値

例

Array.from('foo');
// ["f", "o", "o"]

const s = new Set(['foo', window]);
Array.from(s);
// ["foo", window]

function f() {
  return Array.from(arguments);
}

f(1, 2, 3);

// [1, 2, 3]

let name = 'foo'
const num_array = Array.from(name, (item, index) => {return index});

console.log(name_array);
// [1, 2, 3]

let new_array = Array.from({length:4}, (item, idx) => { return index; });

console.log(new_array)
// [0, 1, 2, 3]