Remove duplicate hashes from two array in js?

Question

There are two array :

arr1 = [
        {name: "gunner", id: 639, label: "group"}, 
        {name: "Gunners", id: 1313, label: "channel", isPrivate: false}
       ]

arr2 = [
        {name: "gunner", id: 639, label: "group"}
       ]

Need to remove all the values from arr1 which exists in arr2 ?

Final arr1 will be, as arr2 already has {name: "gunner", id: 639, label: "group"}:

arr1 = [
        {name: "Gunners", id: 1313, label: "channel", isPrivate: false}
       ]

I tried this but doesn't work as expected.

arr1 = arr1.filter(function(val) {
  return arr2.indexOf(val) == -1;
});

CertainPerformance · Accepted Answer · 2019-12-30 05:48:51Z

If the property order is predictable, make a Set of the stringified items in arr2 first, then filter by whether the stringified item in arr1 exists in that set:

const arr1 = [
  {name: "gunner", id: 639, label: "group"}, 
  {name: "Gunners", id: 1313, label: "channel", isPrivate: false}
];
const arr2 = [
  {name: "gunner", id: 639, label: "group"}
];
const arr2Set = new Set(arr2.map(JSON.stringify));

const output = arr1.filter(obj => !arr2Set.has(JSON.stringify(obj)));
console.log(output);

If you don't want to or can't stringify, then iterate over each of the Object.entries of the object instead, and check that not every entry matches in the other array:

const arr1 = [
  {name: "gunner", id: 639, label: "group"}, 
  {name: "Gunners", id: 1313, label: "channel", isPrivate: false}
];
const arr2 = [
  {name: "gunner", id: 639, label: "group"}
];

const output = arr1.filter((obj1) => {
  const entries1 = Object.entries(obj1);
  return arr2.every(obj2 => (
    entries1.length !== Object.keys(obj2).length ||
    entries1.some(([key, val]) => obj2[key] !== val)
  ));
});

console.log(output);

grean_small_potato · Accepted Answer · 2019-12-30 05:46:33Z

0

You should compare the id in those objects but not the object reference.

const idsInArr2 = arr2.map(val => val.id);
arr1 = arr1.filter(val => idsInArr2.indexOf(val.id) === -1);

answered Dec 30, 2019 at 5:46

grean_small_potato

435 bronze badges

Comments

Tân · Accepted Answer · 2019-12-30 05:50:18Z

0

You can use JSON.stringify to compare objects inside the loop:

var arr1 = [
  {name: "gunner", id: 639, label: "group"}, 
  {name: "Gunners", id: 1313, label: "channel", isPrivate: false}
];

var arr2 = [
  {name: "gunner", id: 639, label: "group"}
];

arr1 = arr1.filter(x => {
  for (var y of arr2) {
    if (JSON.stringify(x) !== JSON.stringify(y)) {
      return y;
    }
  }
});

console.log(arr1);

answered Dec 30, 2019 at 5:50

Tân

1

Comments

diwakersurya · Accepted Answer · 2019-12-30 05:53:15Z

0

Try this:

const arr1 = [
        {name: "gunner", id: 639, label: "group"}, 
        {name: "Gunners", id: 1313, label: "channel", isPrivate: false}
       ]
const arr2 = [
        {name: "gunner", id: 639, label: "group"}
       ]

const arr3 = arr1.filter(function(objArr1) {
  return arr2.findIndex(objArr2=>objArr2.id===objArr1.id) === -1;
});

answered Dec 30, 2019 at 5:53

diwakersurya

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