1、 模板字符串
let str = '明天天气会更好!'; let className = 'test'; let html = `<html> <head></head> <body> <p>今天的天气很好!</p> <div class="${className}">${str}</div> </body> </html>`;
2、数组的扩展
Array.from(obj)将伪数组转化为真数组
<ul> <li>1111</li> <li>1111</li> <li>1111</li> <li>1111</li> <li>1111</li> <li>1111</li> </ul> <script> let allLis = document.querySelectorAll('li'); console.log(allLis); //NodeList(6) [li, li, li, li, li, li] console.log(Array.isArray(allLis)); //false console.log(Array.from(allLis)); //(6) [li, li, li, li, li, li] console.log(Array.isArray(Array.from(allLis))); //true let obj = {'name': '张三'}; console.log(Array.from(obj)); //空数组[] </script>
Array.of()：将传进来的多个参数组成一个数组返回
console.log(Array.of(1, 2, 3, 4)); //(4) [1, 2, 3, 4] console.log(Array.of('张三', '李四', '王五')); //(3) ["张三", "李四", "王五"]
3、对象的扩展
当key 和 value是一样的时候,写一个就够了
let name = '张三'; let age = 18; let person = { name, age }; /* 等效于 let person = { 'name': name, 'age': age } */
Object.assign()：多个对象合并，返回合并后的对象
let obj1 = {name: '张三'};
let obj2 = {age: 18};
let obj3 = {sex: '男'};
let obj4 = {sex: '女'};
let obj = {};
Object.assign(obj, obj1, obj2, obj3, obj4);
console.log(obj); //{name: "张三", age: 18, sex: "女"}
Object.assign(obj, {name: "李四", age: 20, sex: "男"});
//后面的同名属性值覆盖前面的
console.log(obj);//{name: "李四", age: 20, sex: "男"}
4、延展操作符
let str = '今天的天气很好!'; let strArr = [...str]; console.log(strArr); //(8) ["今", "天", "的", "天", "气", "很", "好", "!"] let student = { name: '张三', age: 18, sex: '男' } person = {...student} console.log(person); //{name: "张三", age: 18, sex: "男"} function sum(...arr){ let sum = 0; for(let i = 0; i < arr.length; i++){ sum += arr[i]; } return sum; } console.log(sum(1,2,3)); //6
小应用：数组去重
let arr = [1, 2, 10, 20, 2, 1]; console.log(new Set(arr)); //Set(4) {1, 2, 10, 20} console.log([...new Set(arr)]); //(4) [1, 2, 10, 20]
5、函数扩展
5.1、形参可设置默认值
5.2、参数形式：最后一个形参可以使用延展操作符
5.3、箭头函数() => {}，是一种匿名函数