ECMAScript 10 新特性

2021-11-16

Object.fromEntries

Object.fromEntries() 方法把键值对列表转换为一个对象。

//二维数组
const result = Object.fromEntries([
  ["name", "尚硅谷"],
  ["xueke", "Java,大数据,前端,云计算"],
]);

//Map
const m = new Map();
m.set("name", "ATGUIGU");
const result = Object.fromEntries(m);

//Object.entries ES8
const arr = Object.entries({
  name: "尚硅谷",
});
console.log(arr);

trimStart 和 trimEnd

// trim
let str = "   iloveyou   ";

console.log(str);
console.log(str.trimStart());
console.log(str.trimEnd());

Array.prototype.flat 与 flatMap

//flat 平
//将多维数组转化为低位数组
const arr = [1, 2, 3, 4, [5, 6]];
const arr = [1, 2, 3, 4, [5, 6, [7, 8, 9]]];
//参数为深度 是一个数字
console.log(arr.flat(2));

//flatMap
const arr = [1, 2, 3, 4];
const result = arr.flatMap((item) => [item * 10]);
console.log(result);

Symbol.prototype.description

//创建 Symbol
let s = Symbol("xxx");

console.log(s.description);//xxx