JSON-对象数组中的对象-如何使用JS解析循环？

Question

If I had this schema:

[{
    "Id": 2,
    "Prizes": [{
        "Id": 5,
        "Status": 0,
        "ClaimCode": "PN0016CXC1WPM64P",
        "User": {
            "FirstName": "John",
            "SecondName": "Doe",
        },
        "DrawId": 2,
        "PrizeId": 22,
        "Prize": null
    }]
}]

How could I get the first name or any value under object User that is in array prizes, that is in the main JSON?

I have tried this:

 const response = JSON.parse(this.responseText);
 response.Prizes[0].User.forEach(function(a) {
     output += `<li>${a.FirstName}</li>`;
 });

But getting the error undefined, I believe it can be extracted but only need right syntax. Or this can't be done with for loop?

Answer 1

First of all Response is an Array and User is an object, this should be working :

const response = JSON.parse(this.responseText);

response.map((resp) => {
    resp.Prizes.map((prize) => {
        output += `<li>${prize.User.FirstName}</li>`;

    })
})

Answer 2

Since you have an array of objects, and inside the object an array of values ( Prizes ), you can use nested Array.forEach() calls to get the internal values, wrap them with a string, and push to the items array:

 const response = [{"Id":2,"Prizes":[{"Id":5,"Status":0,"ClaimCode":"PN0016CXC1WPM64P","User":{"FirstName":"John","SecondName":"Doe"},"DrawId":2,"PrizeId":22,"Prize":null}]}]; const items = []; response.forEach((o) => o.Prizes.forEach((p) => items.push(`<li>${p.User.FirstName}</li>`) )); list.innerHTML = items.join(''); 

 <ul id="list"></ul> 

Answer 3

As you have multidimensional array and you need to use Prizes as inside of array.

So first you can combine all Prizes into one using reduce() and the Spread_syntax then after you use map() with join mehod to get the required result.

DEMO

 const response = [{"Id":2,"Prizes":[{"Id":5,"Status":0,"ClaimCode":"PN0016CXC1WPM64P","User":{"FirstName":"John","SecondName":"Doe"},"DrawId":2,"PrizeId":22,"Prize":null}]}]; let res = response.reduce((r,{Prizes}) =>[...r,...Prizes],[]).map(({User})=>`<li>${User.FirstName}</li>`).join(''); document.querySelector('ul').innerHTML =res ; 

 <ul></ul>