js中数组常用遍历,VUE 中 数组常用遍历方法
/* 1,filter 循环 会返回一个新的数组 2,循环次数为是整个数组的长度 */ let filArr = [1,2,3,4,5,6] let newFilArr = filArr.filter( (item,i) =>{ console.log("循环==i==",i); return item >= 3 } ) console.log("newFilArr==",newFilArr)
/* 1,some 循环 会返回一个true 或false 2,当条件满足时,就会终止循环,并返回ture,如果没有满足判断条件,会遍历整个循环 */ let someArr = [1,2,3,4,5,6] let newSomeArr = someArr.some( (item,i) =>{ console.log("some循环==i==",i); return item >= 3 } ) console.log("newSomeArr==",newSomeArr)

let mapArr = ['one','two','three'] let newMapArr = mapArr.map((item,i) => { console.log("map循环==i==",i); return item === 'two' }) console.log("mapArr==",mapArr) console.log("newMapArr==",newMapArr)

let mapArr = ['one','two','three'] let newMapArr = mapArr.map((item,i) => item += ',haha') console.log("mapArr==",mapArr) console.log("newMapArr==",newMapArr)

如下案例:给每个对象中添加age属性
let forArr = [{name:'tom',sex:'man'},{name:'linda',sex:'woman'},] forArr.forEach((item,i) => { console.log("forEach循环==i==",i); item.age = 27 }) console.log("forArr==遍历后===",forArr)

如下面3个案例所示 //案例1: 返回uundefined let findArr = [{name:'tom',sex:'man'},{name:'linda',sex:'woman'},{name:'Join',sex:'man'},] let perObj = findArr.find((item,i) => { console.log("findArr循环==i==",i); return item.name === 'linda3' }) console.log("perObj===",perObj) //案列2 let ages = [3, 10, 18, 20]; let newAge = ages.find(item => item>10) console.log("最后数据==",newAge); //案列3 const arr = [{name:"Jim",age:"20"},{name:"Lily",age:"18"},{name:"Mei",age:"18"},] let age18s = arr.find((item,i)=>{ console.log("findArr循环222==i==",i); return item.name === 'Lily' }) console.log("age18s==",age18s);

const arrIndex = [{name:"Jim",age:"20"},{name:"Lily",age:"18"},{name:"Mei",age:"18"},] let index = arrIndex.findIndex((item,i)=>{ console.log("findIndex==循环次数i==",i); return item.name === 'Lily' }) console.log("index==",index);

let everyArr = [{name:'tom',sex:'man'},{name:'linda',sex:'woman'},{name:'Join',sex:'man'},] let isEvery = everyArr.every((item,i) => { console.log("every循环次数==i==",i); return item.sex === 'woman' }) console.log("isEvery===",isEvery)

some() 和every() 有点类似
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