js 的一些简写方式

1.解构赋值

let arr = [1,2];
let [one,two] = arr;
console.log(one);   //1
console.log(two);   //2

2.fro循环

let arr[1,2,3];
for(let a of arr){
    console.log(a)
}
//打印结果 1,2,3

3.短路求值 ||

function ment(b){
    return b||c;
 }
 console.log( ment() )  //c
 console.log( ment(b) ) //b

4.将字符传转换为整数

let num = +'5';
console.log( num )            //=> 5
console.log( typeof num )     //=> "number" 
console.log( +"5" === 5 )   //=> true