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"]

• Ivar: Does this answer your question? How to get unique values in an array
• Joshua: What do you mean by object method
• DBS: Are you saying you want to be able to do something like ["A", "B"].removeDupe()?

Answer 1

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"]

• KcH: may i know any advantages of doing so ? or just to answer OP Q ?
• Nina Scholz: it is fast, because if has O(1) for addressing the object.

Answer 2

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())

Answer 3

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

Answer 4

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