Find Unique Number from array in JavaScript

Question

Please let me know is this a best approach to find unique number from an array?

var singleNumber = function(nums) {
  for (var i = 0; i < nums.length; i++) {
    if (i === 0) {
      nums[0] = 0 ^ nums[0];
      /* console.log(nums[0]); */
    } else {
      nums[0] ^= nums[i];
      /* console.log(nums[0]); */
    }

  }
  console.log(nums[0]);
  return nums[0];


};

singleNumber([2, 2, 3, 3, 4]);

If you have any better approach with this, help me out.

Possible duplicate of [Get all unique values in an array (remove duplicates)](https://stackoverflow.com/questions/1960473/get-all-unique-values-in-an-array-remove-duplicates) — icecub, May 10 '18 at 01:29
It returns `5` with input `[2, 2, 3, 1, 3, 4]` and `2` for `[2, 2, 3, 1, 3, 3]`maybe there's a better method. — Mark, May 10 '18 at 01:36
@icecub did you check the above question carefully? It is not duplicate. — Vikasdeep Singh, May 10 '18 at 02:44

score 2 · Answer 1 · answered May 10 '18 at 10:05

I've created two functions that return unique numbers from a passed array:

var getFirstUniqueNumber = function(nums) {
    var number = null;
    var map = {};
    nums.forEach((val) => {
        if (!map[val] && (number === null)) number = val;
        if (map[val] && (number !== null)) number = null;
        map[val] = true;
    });
    return number;
};

var getLastUniqueNumber = function(nums) {
    var number = null;
    var map = {};
    nums.forEach((val) => {
        if (!map[val]) number = val;
        map[val] = true;
    });
    return number;
};

I've created a Fiddle here: https://jsfiddle.net/u88qgxrr/2/

They do what the name says, you probably want the last unique number!

Find Unique Number from array in JavaScript

1 Answers1