How to delete items from object array where some keys have duplicate value?

Question

I want to delete rows from an object array that have the same id, but other keys are different. For example, I have the following Array:

testArray = [
 {id: 1, type: 1}
 {id: 2, type: undefined}
 {id: 3, type: 0}
 {id: 3, type: undefined}
 {id: 4, type: 0}
];

testArray[2] and testArray[3] have the same id value, but I want to delete the one that has the type undefined. Final array should look like:

testArray = [
 {id: 1, type: 1}
 {id: 2, type: undefined}
 {id: 3, type: 0}
 {id: 4, type: 0}
];

Please visit help center, take tour to see what and How to Ask. Do some research, search for related topics on SO; if you get stuck, post a minimal reproducible example of your attempt, noting input and expected output. — mplungjan
– mplungjan, Commented Apr 15, 2020 at 13:51
@RaduPopa, the problem is quite more simple than the referenced question, because here is only one property relevant, and not all. — Nina Scholz
– Nina Scholz, Commented Apr 15, 2020 at 14:02
the type of the second object is undefined too. Do you want to remove duplicate objects? If so which one should remove? — Alan Paul Mathew
– Alan Paul Mathew, Commented Apr 15, 2020 at 14:06
@AlanPaulMathew Remove all dupes, preferring undefined but leave them in if not dupes — mplungjan
– mplungjan, Commented Apr 15, 2020 at 14:15

Nina Scholz · Accepted Answer · 2020-04-15 14:35:37Z

2

You could seach for same id in the result set and replace if the former type is undefined.

var array = [{ id: 1, type: 1 }, { id: 2, type: undefined }, { id: 3, type: undefined }, { id: 3, type: 0 }, { id: 4, type: 0 }],
    result = array.reduce((r, o) => {
        var index = r.findIndex(q => q.id === o.id)
        if (index === -1) r.push(o);
        else if (r[index].type === undefined) r[index] = o;
        return r;
    }, []);

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

edited Apr 15, 2020 at 14:35

answered Apr 15, 2020 at 14:05

Nina Scholz

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Comments

mplungjan · Accepted Answer · 2020-04-16 05:51:09Z

1

Try this

const testArray = [
 {id: 1, type: 1},
 {id: 2, type: undefined}, 
 {id: 3, type: undefined},
 {id: 3, type: 0},
 {id: 4, type: 0}
];

let newArray = [];
testArray.forEach(item => {
  const newArrayIndex = newArray.findIndex(newItemArray => newItemArray.id === item.id);
  if (newArrayIndex < 0) return newArray.push(item);
  if (item.type === undefined) return
  newArray[newArrayIndex].type = item.type;
});

console.log(newArray)

edited Apr 16, 2020 at 5:51

mplungjan

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answered Apr 15, 2020 at 14:44

Alan Paul Mathew

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1 Comment

mplungjan Over a year ago

Same as Nina's but without a reduce.

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