JavaScript – Get the unique object from array of objects

October 29, 2022

let obj = [
    { id : 1 },
    { id : 10 },
    { brand : 12 },
    { id : 15 },
    { id : 18 },
    { image_link : 'some link' },
    { price : 10 },
    { brand : 111 },
    { image_link : 'some link 2' }
];

I have this array of object. I want filter this object so that I can get an object without duplicate keys.

I am trying this:

let uniqueIds = [];

let unique = obj.filter( (element ) => {
    
    let key = Object.keys(element)[0];                
    let isDuplicate = uniqueIds.includes(element.key);

    if (!isDuplicate) {
        uniqueIds.push(element.key);
        return true;
    }
    return false;   
});

console.log( unique )

But everytime it’s showing me :

[ { id: 1 } ]

My expected output:

[
    { id : 18 },
    { price : 10 },
    { brand : 111 },
    { image_link : 'some link 2' }
];

>Solution :

You can filter your array based on whether the object’s key is the last occurrence of that key (checked using lastIndexOf) in the array:

let obj = [
    { id : 1 },
    { id : 10 },
    { brand : 12 },
    { id : 15 },
    { id : 18 },
    { image_link : 'some link' },
    { price : 10 },
    { brand : 111 },
    { image_link : 'some link 2' }
];

const keys = obj.map(o => Object.keys(o)[0])

const result = obj.filter((o, i) => keys.lastIndexOf(Object.keys(o)[0]) == i)

console.log(result)