ES6(数组)

map(映射)

例1

    let arr=[12,4,67]

        let result=arr.map(item=>item*2) //箭头函数

        console.log(result) //[24, 8, 134]

例2

let score=[12,67,99]

        let result=score.map(item=>item>=60?"及格":"不及格") //箭头函数+if/else简写

        console.log(result) //["不及格", "及格", "及格"]

reduce(汇总)

let arr=[12,69,180,8763]
        let result=arr.reduce(function(tmp,item,index){ //tmp:12->81->261
         return tmp+item                                //item:69->180->8763                 
        })                                              //index:1->2->3
                                                        //return:81->261->9024
        console.log(result)  //9024

filter(过滤器)

例1

let arr=[12,5,8,99,27,36,75]

        let result=arr.filter(item=>item>=30?true:false)
        console.log(result) //[99,36,75]

例2

let arr=[
       {name:"Li",price:100},
       {name:"Ka",price:200},
       {name:"Ii",price:700},
       {name:"PY",price:400},
        ]

        let result=arr.filter(item=>item.price>200?true:false)

        console.log(result)//[{name:"Ii",price:700},{name:"PY",price:400}]

foreach(遍历,无返回值)

let arr=[12,5,8,99,27,36,75]

        arr.forEach(item=>{console.log(item+1)})