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JavaScript Get the index of an object by its property

Last Updated : 14 Oct, 2025
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Given an object, the task is to get the object's index from the array of objects of the given property name and property value using JavaScript. we're going to discuss a few techniques.

[Approach 1]: Using Array map()

The map() method creates a new array by applying a function to each element. You can then use this array to find the index.

JavaScript 
let arrayObj = [{
    prop_1: 'val',
    prop_2: 'val_12',
    prop_3: 'val_13'
}, {
    prop_1: 'val',
    prop_2: 'val_22',
    prop_3: 'val_23'
}];

function findIndexInArray() {
    let prop = 'prop_2';
    let val = 'val_22';
    console.log("Index of prop = "
        + prop + " val = " + val +
        " is = " +
        arrayObj.map(function (e) {
            return e.prop_2;
        }).indexOf(val));
}

findIndexInArray();

Output
Index of prop = prop_2 val = val_22 is = 1

Syntax:

array.map(function(currentValue, index, arr), thisValue)

[Approach 2]: Using for loop

Using for loop we can iterate over the array of objects and check the given value of prop matches or not.

JavaScript 
let arrayObj = [{
    prop_1: 'val',
    prop_2: 'val_12',
    prop_3: 'val_13'
}, {
    prop_1: 'val',
    prop_2: 'val_22',
    prop_3: 'val_23'
}];

function fun(array, attr, value) {
    for (let i = 0; i < array.length; i += 1) {
        if (array[i][attr] === value) {
            return i;
        }
    }
    return -1;
}

function print() {
    let prop = 'prop_2';
    let val = 'val_22';

    console.log("Index of prop = '" +
        prop + "' val = '" + val + "' is = "
        + fun(arrayObj, prop, val));
}

print();

Output
Index of prop = 'prop_2' val = 'val_22' is = 1

Syntax:

for (initialization; condition; increment/decrement) {
    // Code to execute in each iteration
}

[Approach 3]: Using findIndex()

The JavaScript Array.findIndex() method is used to return the first index of the element in a given array that satisfies the provided testing function (passed in by the user while calling). Otherwise, if no data is found then the value of -1 is returned.

JavaScript 
let arrayObj = [{
    prop_1: 'val',
    prop_2: 'val_12',
    prop_3: 'val_13'
}, {
    prop_1: 'val',
    prop_2: 'val_22',
    prop_3: 'val_23'
}];

const index = arrayObj.findIndex(object => {
    return object.prop_3 === 'val_23';
});

console.log(index);

Output
1

Syntax:

array.findIndex(callback(element, index, array), thisArg)

[Approach 4]: Using some()

The JavaScript arr.some() method checks whether at least one of the elements of the array satisfies the condition checked by the argument method. 

JavaScript 
let arrayObj = [{
    prop_1: 'val',
    prop_2: 'val_12',
    prop_3: 'val_13'
}, {
    prop_1: 'val',
    prop_2: 'val_22',
    prop_3: 'val_23'
}];

let index;

arrayObj.some((object, idx) => {
    if (object.prop_2 === 'val_12') {
        index = idx;
        return true;
    }
});

console.log(index);

Output
0

Syntax:

array.some(callback(element, index, array), thisArg)

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PranchalKatiyar
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