find all duplicates in an array in Angular 8

Question

I am trying to find all the duplicates in the attachmentForms list in Angualar 8. I searched through a few posts and below is the code that I could come up with but I am still unable to set isDuplicate as true for name: Document1. I appreciate any help on this.

export interface AttachmentForm {
  name: string;
  isDuplicate: boolean;
}

  ngOnInit() {
    this.attachmentForms = [
      {name: 'Document1', isDuplicate: false},
      {name: 'Document2', isDuplicate: false},
      {name: 'Document1', isDuplicate: false},
      {name: 'Document3', isDuplicate: false},
    ];
   this.findDuplicates() ;
  }
 findDuplicates() {
    const newArr: AttachmentForm[] = [];
    this.attachmentForms.forEach((item, index) => {
      if (newArr.findIndex(i => i.name === item.name) === -1) {
        item.isDuplicate = false;
      } else {
        item.isDuplicate = true;
      }
      newArr.push(item);
    });
    this.attachmentForms = newArr;
  }

Is findDuplicates getting called? Also you don't need to do newArr.push(item); in both the if and else statement you can just do it after both statements since a conditional statement is synchronous. Much like whatever comes after a for loop. — Matt Croak
– Matt Croak, Commented Nov 18, 2019 at 15:48
@MattCroak I have updated the question according addressing your comments, thank you for letting me about the changes — Varun
– Varun, Commented Nov 18, 2019 at 16:49

Damian C · Accepted Answer · 2019-11-18 20:30:22Z

2

Try changing findDuplicates() to this.findDuplicates()

ngOnInit() {
    this.attachmentForms = [
        { name: 'Document1', isDuplicate: false },
        { name: 'Document2', isDuplicate: false },
        { name: 'Document1', isDuplicate: false },
        { name: 'Document3', isDuplicate: false },
    ];
    this.findDuplicates();
}

findDuplicates() {
    const newArr: AttachmentForm[] = [];
    this.attachmentForms.forEach((item) => {
        if (this.attachmentForms.filter(i => i.name === item.name).length > 1) {
            item.isDuplicate = true;
        } else {
            item.isDuplicate = false;
        }
        newArr.push(item);
    });
    this.attachmentForms = newArr;
}

Here is a Stackblitz example: https://stackblitz.com/edit/angular-nl8zxc

edited Nov 18, 2019 at 20:30

answered Nov 18, 2019 at 15:12

Damian C

2,1812 gold badges16 silver badges18 bronze badges

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

3 Comments

Varun Over a year ago

Not adding this while calling findDuplicates was a editing mistake from my side while posting this question. Thank you for letting me know.t I am still unable to set isDuplicate as true for name: Document1. Can you please help

Varun Over a year ago

Only one Document1 row has isDuplicate = true, other Document1 row has isDuplicate =false with the current code. @3limin4t0r and @shareedit gave a better solution where both Document1 row has isDuplicate = true, unfortunately they deleted the answer: Below is the code:

const counter = new Map(); this.attachmentForms     .forEach(({name}) => counter.set(name, (counter.get(name) || 0) + 1)); this.attachmentForms     .forEach(item => (item.isDuplicate = counter.get(item.name) !== 1));

Damian C Over a year ago

I've update the stackblitz and example code to produce the results you were looking for. I tried the code you posted, but it did not yield the results you wanted in my stack blitz. It's possible I missed a line

Collectives™ on Stack Overflow

find all duplicates in an array in Angular 8

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related