how to find the index of an json Object in an array using Javascript

Question

I have an array like below

let formulaArray = ["(", "(", "(", "2", "+", "3", ")", "*", "3", ")", "+", "(", "12", "/",{}]
 }

json object in an array can be at any index.Now,I want to find the index of json object ,how can i do that?

please change the data structure to a valid one. objects does not contain items without any key and arrays does not have keys in literal notation. — Nina Scholz, Jan 26 '19 at 09:12
There is no such thing as a JSON object. Are you asking how to find the index of the `{}`? — , Jan 26 '19 at 09:18

Alvin Theodora · Answer 1 · 2019-01-26T12:26:59.843

2

Use .forEach() and then check the object with typeof operator, if true, then push it to an array

var formulaArray = ["(",{}, "(", "(", "2", "+", "3", ")", "*", "3", ")", "+", "(", "12", "/",null,{}]
var objectIndex = [];
formulaArray && formulaArray.forEach(function(item, index){
    typeof item==='object' && item!==null && 
objectIndex.push(index);
})
console.log(objectIndex)

edited Jan 26 '19 at 12:26

answered Jan 26 '19 at 09:17

Alvin Theodora

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I think you should return `typeof item === 'object' && item !== null` instead because if the item in the array is `null` it will use that as the index – Nick Parsons Jan 26 '19 at 09:19
I have added `formulaArray &&` to check if the array is null – Alvin Theodora Jan 26 '19 at 09:30
1

Oh, got it, I misunderstood what you meant, thanks – Alvin Theodora Jan 26 '19 at 10:10
Thank You! but this is not working for number of objects,it is returning only the index for the first object – valli Jan 26 '19 at 12:18
I have edited the code, now it finds all index and push it to an array – Alvin Theodora Jan 26 '19 at 12:27

score 0 · Answer 2 · answered Jan 26 '19 at 10:24

Please check out this SO answer https://stackoverflow.com/a/36419269/3902739

It defines the correct structure of an array of Json objects and uses JavaScript functions such as Array.find or Array.forEach or Array.filter as clearly explained in the example provided.

Hope this helps!

how to find the index of an json Object in an array using Javascript

2 Answers2