Usage of some, every, find, FindIndex

some、every、find、findIndex、reduce Usage of

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Preface

From the beginning for Loop traversal method , Later, various traversal methods emerged in endlessly , In fact, the biggest difference is the application scenario . What we need to remember most is , Under what circumstances, which method is more appropriate ..

Array data

var potatos = [{
     id: '1001', weight: 50 },
{
     id: '1002', weight: 80 },
{
     id: '1003', weight: 120 },
{
     id: '1004', weight: 40 },
{
     id: '1005', weight: 110 },
{
     id: '1006', weight: 60 }]

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Tips ： The following is the main body of this article , The following cases can be used for reference

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some

var hasbig = potatos.some(potato => {
     return potato.weight > 100 })

//true

our some fellow , Just find a qualified , Just come back and report true So it won't be all traversed , Don't do extra work （ Excellent performance ), The return result is Boolean .

every

var allbig = potatos.every(potato => {
     return potato.weight > 100 })

//false

Traverse each element , If any element fails to meet the condition, it will return false, If the element that does not meet the condition is not found after traversal , Then all meet the conditions , return true

find

var big = potatos.find(potato => {
     return potato.weight > 100 })

//{ id: '1003', weight: 120 }

find and some Is very similar , Are looking for qualified , One can however some I went in for a search and came back to report “ Yes ”（true）, and find Then return the whole data （ Returns the first qualified object ）

findIndex

var i = potatos.findIndex(potato=>{
     return potato.weight > 100 })

//2

find Twin brother , however find What is returned is data , and find The index value of the main sentence is returned

summary

Traversal data , Query the data that meets the conditions , But it's confusing

In this paper, the reference ：https://juejin.cn/post/6844903870154588168