JavaScript - Get the unique object from array of objects

Question

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' }
];

what is the expected output?

Amila Senadheera
– Amila Senadheera

2022-10-29 06:28:52 +00:00
Commented Oct 29, 2022 at 6:28 — Amila Senadheera
– Amila Senadheera, Commented Oct 29, 2022 at 6:28
brnad is not brand

flyingfox
– flyingfox

2022-10-29 06:32:41 +00:00
Commented Oct 29, 2022 at 6:32 — flyingfox
– flyingfox, Commented Oct 29, 2022 at 6:32

Nick · Accepted Answer · 2022-10-29 06:37:24Z

3

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)

edited Oct 29, 2022 at 6:37

answered Oct 29, 2022 at 6:31

Nick

147k23 gold badges67 silver badges106 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

Shibbir Over a year ago

I have added my exptected output on my question. Can you check it please?

Nick Over a year ago

@Shibbir please see my edit, that matches your required output

Nick Over a year ago

@Shibbir good to hear! :)

Shibbir Over a year ago

one more help. Can I remove the keys which value is empty?

Nick Over a year ago

@Shibbir sorry, I misinterpreted what you wanted. I thought for that sample data you would want { id : 18 } in the output instead of { id : '' }, not to remove id completely. In that case you should add the filter on result instead i.e. const result = obj.filter((o, i) => keys.lastIndexOf(Object.keys(o)[0]) == i).filter(o => Object.values(o)[0])

|

flyingfox · Accepted Answer · 2022-10-29 06:31:57Z

1

The reason is that you need to use key instead of element.key

Note: it seems you have a typo brnad is not brand

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' }
];

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

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

console.log( unique )

edited Oct 29, 2022 at 6:31

answered Oct 29, 2022 at 6:30

flyingfox

13.5k4 gold badges30 silver badges43 bronze badges

4 Comments

Shibbir Over a year ago

I have added my exptected output on my question. Can you check it please?

flyingfox Over a year ago

@Shibbir I change brnad to brand, you can check it now again

Shibbir Over a year ago

Can you please check my exptected output on my questions?

flyingfox Over a year ago

@Shibbir so you want to the latter key to override previous,in this case forEach might be a better choice or as Nick's answer

Amila Senadheera · Accepted Answer · 2022-10-29 06:36:54Z

0

You have used element.key in two places it should be just key.

And since you need the final duplicate element you need to do a reverse of the input array and again do another reverse to unique 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' }
];

let uniqueIds = [];

// reverse the input array before start filtering
obj.reverse()

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

    if (!isDuplicate) {
        uniqueIds.push(key);
        return true;
    }
    return false;   
});
// to make the output order according to the input array
unique.reverse()
// to make the input array to the initial order 
obj.reverse()

console.log(unique)

edited Oct 29, 2022 at 6:36

answered Oct 29, 2022 at 6:31

Amila Senadheera

13.4k16 gold badges31 silver badges48 bronze badges

1 Comment

Shibbir Over a year ago

id should be 18

Collectives™ on Stack Overflow

JavaScript - Get the unique object from array of objects

3 Answers 3

7 Comments

4 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

7 Comments

4 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related