配列の展開
const value = [2, 3, 1, 4, 5]; console.log(Math.max(...value));
シャローコピー
// 配列の複製 let a = [1, 2, 3]; let b = [...a]; console.log(b); //[ 1, 2, 3 ] // シャローコピーなので多次元配列やオブジェクト等は影響を受けてしまう let c = [[1], [2], [3]]; let d = [...c]; c[0][0] = 0; console.log(c); // [ [ 0 ], [ 2 ], [ 3 ] ]
配列の連結
let a = [0, 1, 2]; let b = [3, 4, 5]; let c = [...a, ...b]; console.log(c); // [ 0, 1, 2, 3, 4, 5 ] a.push(...b); console.log(a); // [ 0, 1, 2, 3, 4, 5 ]
配列の分割代入
let [a, ...other] = [1, 2, 3]; console.log(a, other); // 1 [ 2, 3 ]
iterableなオブジェクトを展開できる
String、NodeList、HTMLCollection等…
let sample = "sample"; console.log([...sample]); // [ 's', 'a', 'm', 'p', 'l', 'e' ]