Question 80222 in Javascript Question posted in
A very good W3school tutorial can be found here.

Remove objects with same ID – Javascript

i have an array like this.

0: {id: 4, country: Japan},
1: {id: 5, country: Korea},
2: {id: 6, country: Philippines},
3: {id: 6, country: Philippines}

How can I remove both record with the same id? so the returned data should look like this.

0: {id: 4, country: Japan},
1: {id: 5, country: Korea}

How can i fix this? I tried the methods described in a specific topic here but it didn’t work

Tags:

3

Answers


  1. 0 
    const data = [
    {id: 4, country: 'Japan'},
    {id: 5, country: 'Korea'},
    {id: 6, country: 'Philippines'},
    {id: 6, country: 'Philippines'}
];

const duplicates = data.filter((obj, index, arr) => {
  return arr.map(mapObj => mapObj.id).indexOf(obj.id) !== index;
});

const uniqueData = data.filter((obj, index, arr) => {
  return arr.map(mapObj => mapObj.id).indexOf(obj.id) === index;
});

console.log("Duplicates:", duplicates);
console.log("Unique data:", uniqueData);
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  2. 0

    For each element of the array if there are elements equal to it, it is marked as "to be removed" and meanwhile the equal elements are removed. The i element is removed at the end.

    function removeDuplicates(a){
  for(let i = 0 ; i < a.length ; i++){
    let toRemove = false;
    for(let j = 0; j < a.length ; j++){
      if(i != j && a[i].id == a[j].id){
        toRemove = true;
        a.splice(j,1);
      }
    }
    if(toRemove) a.splice(i,1)
  }
  return a;
}
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  3. 0

    this is another way to do that

    let data = 
[
{id: 4, country: "Japan"},
{id: 5, country: "Korea"},
{id: 6, country: "Philippines"},
{id: 6, country: "Philippines"}

]; 

data.map((s, i) => {
 if (i>0 &&s.id != data[i- 1].id) {
  return s;
 }else{
  delete data[i- 1];
 }
});
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