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javascriptarrays
MrCycling
MrCycling

Reputation: 3004

Javascript: Remove duplicate objects from array with conditions

I have an array that looks like:

var array = [
  { name: "product1", rating: 1 },
  { name: "product3", rating: 2 },
  { name: "product1", rating: 2 },
  { name: "product2", rating: 2 },
  { name: "product3", rating: 1 },
  { name: "product4", rating: 2 },
  { name: "product2", rating: 2 }
]

I am wanting to eliminate objects with duplicate names, BUT want to keep the one with the lowest rating. Thus ending up with:

var newarray = [
  { name: "product1", rating: 1 },
  { name: "product2", rating: 2 },
  { name: "product3", rating: 1 },
  { name: "product4", rating: 2 }
]

Using filter I end up with two product1 & product3 in the newarray due to different ratings. Targeting by name, I end up with the object in the array based on its original position, which would not work.

I am looking for a way with vanilla javascript to compare the value for each of the duplicated objects and push the one with the lowest value.

Each product name could appear up to three times. Values would only be 1 or 2.

Upvotes: 0

Views: 70

Answers (2)

Dillon Burnett
Dillon Burnett

Reputation: 503

Since reduce is already mentioned, I thought I would give an example of using .filter() as you get some flexibility in a different area.

var array = [
  { name: "product1", rating: 1 },
  { name: "product3", rating: 2 },
  { name: "product1", rating: 2 },
  { name: "product2", rating: 2 },
  { name: "product3", rating: 1 },
  { name: "product4", rating: 2 },
  { name: "product2", rating: 2 }
];
var newArray = array.filter((value,iteration,arr)=>{
    for(var i = 0; i < arr.length; i++){
        if(value.name === arr[i].name && iteration != i){
            if(value.rating > arr[i].rating){
                return false
            }else if(value.rating === arr[i].rating && iteration > i){
                return false
            }
        }
    }
    return true
});
/*newArray
[
    { name: 'product1', rating: 1 },
    { name: 'product2', rating: 2 },
    { name: 'product3', rating: 1 },
    { name: 'product4', rating: 2 }
]*/

Reduce should be faster in most cases, but you never know.

Upvotes: 0

hgb123
hgb123

Reputation: 14891

You could use reduce to group by name with the element has lowest rating of each name

const array = [
  { name: "product1", rating: 1 },
  { name: "product3", rating: 2 },
  { name: "product1", rating: 2 },
  { name: "product2", rating: 2 },
  { name: "product3", rating: 1 },
  { name: "product4", rating: 2 },
  { name: "product2", rating: 2 },
]

const res = Object.values(
  array.reduce((acc, el) => {
    if (!acc[el.name] || acc[el.name].rating > el.rating) {
      acc[el.name] = el
    }
    return acc
  }, {})
)

console.log(res)

Upvotes: 3

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