Spread operator (JavaScript)

An ES6 feature that provides alternative syntax for using iterable values.

Destructuring

const [a, b, c] = 'abc';
c

'c'

const [first, ...rest] = [1, 2, 3];
first

rest

[2, 3]

const nums = [1, 2, 3];
Math.max(...nums);

const abc = ['a', 'b', 'c'];
const def = ['d', 'e', 'f'];

[...abc, ...def];

['a', 'b', 'c', 'd', 'e', 'f']

The spread operator only requires that the values are iterable. We don't have to use arrays.

const hij = ['h', 'i', 'j'];
const klm = 'klm';
[...hij, ...klm];

['h', 'i', 'j', 'k', 'l', 'm']