CODEWITHSUNDEEP
javascriptarrays
Shane
Shane

Reputation: 5677

Removing duplicate values from two arrays

existing ["562fae5a626ca2e032947baa"]

new array [ { _id: '562fae5a626ca2e032947baa' },
  { _id: '562fae57626ca2e032947ba9' } ]

modified [ { _id: '562fae5a626ca2e032947baa' },
  { _id: '562fae57626ca2e032947ba9' } ]

I have an existing array and a new array, i want to compare the existing and the new array and remove the duplicates.

var existing = ["562fae5a626ca2e032947baa"];
var newArr = [ { _id: '562fae5a626ca2e032947baa' },
      { _id: '562fae57626ca2e032947ba9' } ];

newArr = newArr.filter(function(val){
    return existing.indexOf(val) == -1;
});

console.log(newArr);

When i try to print newArr, i still get the two objects?

modified [ { _id: '562fae5a626ca2e032947baa' },
  { _id: '562fae57626ca2e032947ba9' } ]

I want the modified array to have only. 

modified [{ _id: '562fae57626ca2e032947ba9' } ]

Below is the fiddle. http://jsfiddle.net/ema6upg1/2/

Upvotes: 0

Views: 53

Answers (3)

James
James

Reputation: 22247

The lookup for an object property is more efficient than iterating an array to find an id. Consider:

var existing = {
  "562fae5a626ca2e032947baa": true
};
var newArr = [ { _id: '562fae5a626ca2e032947baa' },
  { _id: '562fae57626ca2e032947ba9' } ];

newArr.filter(function(val) {
  return existing[val._id] || false;
}

Upvotes: 0

Watte
Watte

Reputation: 312

Your problem is, that one array contains objects.

var existing = ["562fae5a626ca2e032947baa"];
var newArr = [ { _id: '562fae5a626ca2e032947baa' },
  { _id: '562fae57626ca2e032947ba9' } ];

newArr = newArr.filter(function(val){

    if(typeof val == "object") {
        return existing.indexOf(val._id) == -1;   
    }

    return existing.indexOf(val) == -1;
});

console.log(newArr);

Upvotes: 1

Saransh Kataria
Saransh Kataria

Reputation: 1497

 newArr.filter(function(val){
    return existing.indexOf(val._id) == -1;
})

is what you need, val is an object, you need to compare its _id

Upvotes: 1

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