Sum of all the non-repeating elements of an array JavaScript

Suppose, we have an array of numbers like this −

const arr = [14, 54, 23, 14, 24, 33, 44, 54, 77, 87, 77, 14];

We are required to write a JavaScript function that takes in one such array and counts the sum of all the elements of the array that appear only once in the array −

For example:

The output for the array mentioned above will be −

356

The code for this will be −

const arr = [14, 54, 23, 14, 24, 33, 44, 54, 77, 87, 77, 14];
const nonRepeatingSum = arr => {
   let res = 0;
   for(let i = 0; i < arr.length; i++){
      if(i !== arr.lastIndexOf(arr[i])){
         continue;
      };
      res += arr[i];
   };
   return res;
};
console.log(nonRepeatingSum(arr));

Following is the output on console −

30