Array: Find sum of two numbers

gistfile1.txt

function findSum(arr, sum) {
  var i = 0;
  var j = arr.length-1;
  var complete = false;
  
  while (complete === false) {

    if(arr[i] + arr[j] === sum) {
      complete = true;
      return [arr[i], arr[j]];
    }

    else if (arr[i] + arr[j] < sum) {
      i++
    }

    else if (arr[i] + arr[j] > sum) {
      j--
    }

    if (i === j) {
      complete = true
      
    }
  }

  return 'No combination found'

}