Check if array of objects contain certain key

Question

I need to determine if a certain key exists in an array of objects.

Here is a sample array:

arrOfObj = [{
        "mainKey1": {
            "subKey1": {
                "innerKey1": {
                    "innerMostKey1": {
                        "key1": "value"
                    }
                }
            }
        }
    }, {
        "mainKey2": {
            "key2": "value"
        }
    }, {
        "mainKey3": {
            "subKey3": {
                "key3": "value"
            }
        }
    }
]

I was trying to do this but I get the wrong output:

const objKeys = Object.keys(arrOfObj)
console.log('objKeys = ' + JSON.stringify(arrOfObj))

Output is the index numbers:

objKeys = ["0", "1", "2"]

I want to have a function that works like this:

var isKeyPresent = checkKeyPresenceInArray('mainKey3')

Please note though that I only need to check the topmost level in the objects - in above example, these are the main keys (mainKey1, etc) and that their content is dynamic (some others have deeply nested object inside and some not so.

Help!

You need to find key of individual object, not the complete array, loop over the array using some array method and the for each individual element get the keys and test it against your desired key — Code Maniac
– Code Maniac, Commented Apr 28, 2020 at 2:04

mickl · Accepted Answer · 2020-04-28 02:02:26Z

13

You can try using array.some():

let checkKeyPresenceInArray = key => arrOfObj.some(obj => Object.keys(obj).includes(key));

let arrOfObj = [{
        "mainKey1": {
            "subKey1": {
                "innerKey1": {
                    "innerMostKey1": {
                        "key1": "value"
                    }
                }
            }
        }
    }, {
        "mainKey2": {
            "key2": "value"
        }
    }, {
        "mainKey3": {
            "subKey3": {
                "key3": "value"
            }
        }
    }
]

let checkKeyPresenceInArray = key => arrOfObj.some(obj => Object.keys(obj).includes(key));


var isKeyPresent = checkKeyPresenceInArray('mainKey3')

console.log(isKeyPresent);

answered Apr 28, 2020 at 2:02

mickl

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Comments

Jordan Soltman · Accepted Answer · 2020-04-28 02:05:42Z

You can iterate through the array, check and see if any of the objects has the key that you are looking for, and return true if it does. If you don't find the key, then the for loop will complete and it will return false.

arrOfObj = [{
        "mainKey1": {
            "subKey1": {
                "innerKey1": {
                    "innerMostKey1": {
                        "key1": "value"
                    }
                }
            }
        }
    }, {
        "mainKey2": {
            "key2": "value"
        }
    }, {
        "mainKey3": {
            "subKey3": {
                "key3": "value"
            }
        }
    }
]

function arrayHasKey(arr, key) {
  for (const obj of arr) {
    if (key in obj) { return true; }
  }
  return false;
}

console.log(arrayHasKey(arrOfObj, "mainKey2"))
console.log(arrayHasKey(arrOfObj, "mainKey10"))

Sohan Patil · Accepted Answer · 2020-05-01 07:24:33Z

0

this will work,it returns boolean value:

arrOfObj.hasOwnProperty('mainKey3');

answered May 1, 2020 at 7:24

Sohan Patil

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1 Comment

Ala Eddine Menai Over a year ago

It returns false even the key exists because it checks properties, not objects.

Ala Eddine Menai · Accepted Answer · 2020-05-01 21:51:06Z

0

You can use some with hasOwnProperty like this :

let checkKeyPresenceInArray = (key) => arrOfObj.some((o) => o.hasOwnProperty(key));

answered May 1, 2020 at 21:51

Ala Eddine Menai

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Comments

Arnab_Datta · Accepted Answer · 2020-05-01 22:12:55Z

0

You have to use hasOwnProperty method to check if the key is available in the objects in that array -

var c = 0;
arrOfObj.forEach(e => {
  if(e.hasOwnProperty("mainKey1")){
       c++;
   }
});
if(c > 0 && c == arrOfObj.length){
    console.log("The key is found in all the objects in the array.");
}
else if(c == 0){
    console.log("The key is not found in any objects in the array");
}
else{
     console.log("The key is  found in some objects in the array");
}

answered May 1, 2020 at 22:12

Arnab_Datta

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Comments

johannesMatevosyan · Accepted Answer · 2022-11-16 11:49:05Z

0

It is possibly to apply JSON.stringify() for that purpose:

let list = [{
        "data1": {
            "subKey1": {
                "innerKey1": {
                    "innerMostKey1": {
                        "key1": "value"
                    }
                }
            }
        }
    }, {
        "data2": {
            "key2": "value"
        }
    }, {
        "data3": {
            "subKey3": {
                "key3": "value"
            }
        }
    }
]

let checkIfInArray = key => list.some(obj => JSON.stringify(obj).indexOf(key) > -1);


var result = checkIfInArray('key2')

alert(result);

answered Nov 16, 2022 at 11:49

johannesMatevosyan

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