SOURCE

//map方法有返回值
let arr = ['子0','子1','子2','子3','子4']
let mapArr = arr.map((item,index)=>{
    return `处理${item}`
})
console.log(mapArr)

//没有返回值，只能依次输出
let forEachPush = []
arr.forEach((item,index)=>{
    return forEachPush.push(`forEach处理${item}`)
})
console.log(forEachPush)

//filter 返回参数函数为真的值
let filterResult = arr.filter((item,index)=>{
    return item === "子2"
})
console.log(filterResult)
let stu = [
    {name:"张三",js:90},
    {name:"李四",js:50},
    {name:"王五",js:60}
]
let newFilterResult = stu.filter((item,index,stu0)=>{
    return item.js>60
})
console.log(newFilterResult)

//返回第一个查询到的为真的值，只要满足就会停止遍历
let findResult = arr.find((item,index)=>{
    return item==="子3"
})

console.log(findResult)
const findArr = [
    {name:"张三",js:90},
    {name:"李四",js:50},
    {name:"王五",js:60},
    {name:"赵六",js:50},
]
let findArrNew=findArr.find((item)=>{
    return item.js==50
})
console.log(findArrNew)

//返回第一个查询到的为真的值的索引，只要满足就会停止遍历
let findIndexResult = arr.findIndex((item,index)=>{
    return item ==="子2"
})
console.log(findIndexResult)
let findIndexArrNew=findArr.findIndex((item)=>{
    return item.js==50
})
console.log("findIndex的索引为"+findIndexArrNew)

let everyArr =[2,3,4]
let everyResult = everyArr.every((item,index)=>{
    return item>0
})
//都符合就返回true
console.log(everyResult)

let someResult = everyArr.some((item,index)=>{
    return item>3
})
//只要有一项为true 就是true
console.log(someResult)

let reduceArr = [0,1,2,3,4]
let reduceResult = reduceArr.reduce((red,obj)=>{
    return red+obj
},0)

console.log(reduceResult)