一些函数

1.sort()

var a = [1,4,2,5,7,9]
a.sort((a1,a2) => a1 < a2)// [9,7,5,4,2,1] 从大到小排列
a.sort((a1,a2) => a2 < a1) //[1,2,4,5,7,9] 从小到大排列
此时a 是排列好的数组

2. forEach()

let b = [1,2,3,4,5]
b.forEach((i) => {
    console.log(i+'2')//12,22,32,42,52
})
此时 b 还是[1,2,3,4,5] 不会改变b的

3. find()

var objArr = [
    {id:1, name:'jiankian'},
    {id:23, name:'anan'}, 
    {id:188, name:'superme'},
    {id:233, name:'jobs'}, 
    {id:288, name:'bill', age:89},
    {id:333}
] ;
var ret2 = objArr.find((v) => {
    return v.id == 233;
});
console.log(ret2);
// return {id:233, name:'jobs'}