剩余參數(shù)允許我們將一個(gè)不定數(shù)量的參數(shù)表示為一個(gè)數(shù)組姻檀。
function sum (first, ...args) {
console.log(first); //10
console.log(args); // [20,30]
}
sum(10, 20, 30)
const sum = (...args) => {
let total = 0;
args.forEach(item => total += item);
return total;
}
剩余參數(shù)和解構(gòu)賦值配合使用
let students = ['王五'铝穷，'張三'性含，'李四'];
let [s1, ...s2] = students;
console.log(s1); // '王五'
console.log(s2); // [ '張三'峦椰，'李四' ]
擴(kuò)展運(yùn)算符
擴(kuò)展運(yùn)算符可以將數(shù)組或者對(duì)象轉(zhuǎn)為用逗號(hào)分隔的參數(shù)序列衩辟。
let ary = [1, 2, 3];
...ary // 1, 2, 3
擴(kuò)展勻運(yùn)算符 可以應(yīng)用于合并數(shù)組
let ary1 = [1, 2, 3];
let ary2 = [4, 5, 6];
let ary3 = [...ary1, ...ary2]
// 防法2
ary1.push(...ary2);
將類數(shù)組或可遍歷對(duì)象轉(zhuǎn)換為真正的數(shù)組
<div>1</div>
<div>2</div>
<div>3</div>
<div>4</div>
<div>5</div>
var oDivs = document.getElementsByTagName('div');
console.log(oDivs)
var ary = [... oDivs];
ary.push('a');
console.log(ary)
