how to delete duplicate records from array of objects?

Question

I have this object in Javascript.

[{"col1": 1, "col2": 25},{"col1": 1, "col2": 25},{"col1": 3, "col2": 30}]

How can I drop duplicate records in order to get this result?

[{"col1": 1, "col2": 25},{"col1": 3, "col2": 30}]

I have tried next logic, but does not work:

[...new Set(myData)]

https://stackoverflow.com/questions/2218999/remove-duplicates-from-an-array-of-objects-in-javascript — Robert, Jan 14 '19 at 01:39

score 1 · Answer 1 · answered Jan 14 '19 at 00:26

1

const a = [{"col1": 1, "col2": 25},{"col1": 1, "col2": 25},{"col1": 3, "col2": 30}];

console.log(
  a.reduce(
    (acc, val) => !acc.some(({col1, col2}) => val.col1 === col1 && val.col2 === col2) 
                  ? acc.concat(val) 
                  : acc, 
     []
  )
);

answered Jan 14 '19 at 00:26

quirimmo

9,800
3
30
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This would be the first option on my mind, so +1 for you! – Shidersz Jan 14 '19 at 00:42

score 1 · Accepted Answer · answered Jan 14 '19 at 00:36

1

I recently read this on another answer and I liked it, this uses the optional argument of filter() that is passed as this inside the filter function.

const input = [
    {"col1": 1, "col2": 25},
    {"col1": 1, "col2": 25},
    {"col1": 3, "col2": 30}
];

let res = input.filter(function({col1, col2})
{
    return !this.has(`${col1}-${col2}`) && this.add(`${col1}-${col2}`)
}, new Set());

console.log(res);

answered Jan 14 '19 at 00:36

Shidersz

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2
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48

1

That's a nice way to use the second argument of `fitler()`. – Mark Jan 14 '19 at 01:40

Jack Bashford · Answer 3 · 2019-01-14T01:42:35.710

1

This answer shows a simple filter operation with a Set:

const data = [{"col1": 1, "col2": 25},{"col1": 1, "col2": 25},{"col1": 3, "col2": 30}];

const unique = data.filter(function({ col1, col2 }) { return !this.has(`${col1}-${col2}`) && this.add(`${col1}-${col2}`)}, new Set);

console.log(unique);

edited Jan 14 '19 at 01:42

answered Jan 14 '19 at 01:21

Jack Bashford

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And just hope you don't have data like: `{"col1": 12, "col2": 3},{"col1": 1, "col2": 23},`? – Mark Jan 14 '19 at 01:34
1

Fixed @MarkMeyer – Jack Bashford Jan 14 '19 at 01:42

how to delete duplicate records from array of objects?

3 Answers3