removing duplicates from array in javascript

Question

var removeDuplicates = function(nums) {
    for(let i=0; i<nums.length; i++){
        for(let j=i+1; j<nums.length; j++){
            if(nums[i]===nums[j]){
                nums.splice(i,1);
            }
        }
    }
};

this is my code for removing the duplicates, it works for number that are repeated twice but does not work for number that is repeated more than 2. Can anyone please tell me what is wrong here? I want to solve this by only using for loops. Input: 0,0,1,1,1,2,2,3,3,4 Output: 0,1,1,2,3,4 Expected: 0,1,2,3,4

But the bug in your code is that the inner loop has to also start from 0, not i+1 — doublesharp, Feb 20 '23 at 16:34

score 3 · Accepted Answer · answered Feb 20 '23 at 16:37

You are removing elements while iterating forwards, so you'll skip an element each time one is removed (due to the indexes shifting down). Loop backwards instead to delete while iterating.
Break out of the inner loop once a matching number is found.

const removeDuplicates = function(nums) {
  for (let i = nums.length - 1; i >= 0; i--) {
    for (let j = 0; j < i; j++)
      if (nums[j] === nums[i]) {
        nums.splice(i, 1);
        break;
      }
  }
};
let arr = [0,0,1,1,1,2,2,3,3,4];
removeDuplicates(arr);
console.log(arr);

Finding the unique elements of an array is much easier to do with a Set:

const uniqueValues = nums =>  [...new Set(nums)];
console.log(uniqueValues([0,0,1,1,1,2,2,3,3,4]));

removing duplicates from array in javascript

1 Answers1