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This article is about how forEach is used in the project. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

ForEach will change the original array that is looped by forEach cannot be empty.

ForEach changes the original array value is the content index is the index array is the array you write.

Function description: eachArr adds a new key value to each item in the array

Why foeach is used in the project. Because forEach changes the original array.

At some point, we need to use the original array.

For example, the backend has only three fields in each item given to us. We need to add another field to control the others. At this point we can use foreach.

EachArr: [

{name: "lj", age: 20}

{name: "lh", age: 23}

{name: "yj", age: 21}

]

GiveEach () {

If (this.eachArr) {

This.eachArr.forEach ((v, I, arr)) = > {

/ / add a new key

This.eachArr [I] ['url'] = "http"

})

Console.log ('123 years, this.eachArr)

}

}

ForEach does not return a value

Let arr= [

{name:' Zhang San', age:13}

{name:' Zhang San', age:13}

{name:' Zhang San', age:13}

]

Let newRrr=arr.forEach ((item,index,arr) = > {

Console.log ("everything", item)

Console.log ("Index", index)

Console.log ("looped array", arr)

Return index

})

/ / because forEach does not return a value, the value is undefined

Console.log ("newRrr", newRrr)

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