[JS] Merge Sort

mergeSort.js

function mergeSort(array) { 
  if(array.length <= 1) return array;
  
  const half = Math.floor(array.length / 2);        
  const left = array.slice(0, half);      
  const right = array.slice(half);       
  const sortedLeft = mergeSort(left);   
  const sortedRight = mergeSort(right); 
  
  return merge(sortedLeft, sortedRight); 
}

function merge(left, right) { 
  let l = 0;
  let r = 0;
  const sorted = []; 
  while(l < left.length && r < right.length) {
    if(left[l] <= right[r]) {
      sorted.push(left[l]); 
      l++;
    }
    else {
      sorted.push(right[r]);
      r++;
    }
  }
  
  if(l < left.length) { 
    for(; l < left.length; l++) sorted.push(left[l]); 
  }
  if(r < right.length) {
    for(; r < right.length; r++) sorted.push(right[r]); 
  }

  return sorted;
}

// -------------------------------------------------- Test --------------------------------------- //
const array = [8, 7, 1, 6, 9, 4, 8];
console.log(mergeSort(array)); // [1, 4, 6, 7, 8, 8, 9]