スリードッツ：スプレッド構文と残余

JavaScript/TypeScript
  • spread: ひろげる

スプレッド構文：

declare var arr1, arr2 : Array<any>;

let concatenated = [...arr1, ...arr2];

// compliler option '-downlevelIteration' is maybe needed
declare var str : string;

const splitedCharArray = [...str];

残余引数：

function foo(first, ...restArgs) {
  // ...
}

分割代入：

let [first, ...rest] = [1, 2, 3, 4]
// first = 1
// rest = [2, 3, 4]