Remove duplicates in the array using an object method

Question

I'm curious how you'd be able to do this by utilizing an object method. Is it possible?

function removeDuplicates(arr) {
  var result = [];

  for (var i = 0; i < arr.length; i++) {
    if (result.indexOf(arr[i]) === -1) {
      result.push(arr[i]);
    }
  }
  return result;
}

console.log(removeDuplicates(['Mike', 'Mike', 'Paul'])); // returns ["Mike", "Paul"]

Does this answer your question? [How to get unique values in an array](https://stackoverflow.com/questions/11246758/how-to-get-unique-values-in-an-array) — Ivar, Dec 03 '20 at 09:38
Are you saying you want to be able to do something like `["A", "B"].removeDupe()`? — DBS, Dec 03 '20 at 09:40

score 2 · Answer 1 · answered Dec 03 '20 at 09:39

2

You could take an object and return only the keys.

function removeDuplicates(arr) {
    const seen = {};

    for (let i = 0; i < arr.length; i++) seen[arr[i]] = true;

    return Object.keys(seen);
}

console.log(removeDuplicates(["Mike", "Mike", "Paul"])); // ["Mike", "Paul"]

answered Dec 03 '20 at 09:39

Nina Scholz

376,160
25
347
392

may i know any advantages of doing so ? or just to answer OP Q ? – KcH Dec 03 '20 at 10:12
1

it is fast, because if has O(1) for addressing the object. – Nina Scholz Dec 03 '20 at 10:15

score 0 · Answer 2 · answered Dec 03 '20 at 09:38

Yes, you could use built-in Set()

const data = ["Mike", "Mike", "Paul"]

const res = Array.from(new Set(data))

console.log(res)

You could utilize by making it a method of the array

Array.prototype.removeDuplicates = function() {
  return Array.from(new Set(this))
}

const data = ["Mike", "Mike", "Paul"]

console.log(data.removeDuplicates())

score 0 · Answer 3 · answered Dec 03 '20 at 09:42

If i understood correctly, you could extend the Array object with a removeDuplicates() method, just like this:

if (!Array.prototype.removeDuplicates) { // Check if the Array object already has a removeDuplicates() method
    Array.prototype.removeDuplicates = function() {
        let result = [];
        for(var i = 0; i < this.length; i++){
            if(result.indexOf(this[i]) === -1) {
                result.push(this[i]);
            }
        }
        return result;
    }
}

const arr = ["Mike", "Mike", "Paul"];
console.log(arr.removeDuplicates()); // Call the new added method

score 0 · Answer 4 · answered Dec 03 '20 at 09:43

0

function removeDuplicates(arr) {
  return Object.keys(
    arr.reduce(
      (val, cur) => ({
        ...val,
        [cur]: true
      }),
      {}
    )
  );
}

console.log(removeDuplicates(['Mike', 'Mike', 'Paul']));

answered Dec 03 '20 at 09:43

michael

4,053
2
12
31

Remove duplicates in the array using an object method

4 Answers4