自带的循环，并且会把处理的值回填对应的位置
let arr=[1,2,3,4,5,6]
let newarr=[];
for(let i=0;i<arr.length;i++){
newarr.push(arr[i]*2);
}
let newarr2=arr.map(function (ele)...
ES6 provides Map, it is a set of k-v pair. Key can be number, string, object, function and even undefined.
var m = new Map();
Methods:
1. set(k,v)
m.set("edition", 6) // 键是字符串
m....
ES6Map All In One
二维数组
字典
ES6Map All In OneMap with initializinginitial value// ✅ 二维数组，作为初始值 const map = new Map([["(", ")"]]);// Map(1) {"(" => ")"}const map = new Map([...
WeakMap: is a type of Map where only objects can be passed as keys. Primitive data type -- such are string, numbers, booleans, etc --- are not allowed.
let user = {};
let comment = {};
let mapSe...
