merge.js

// Merge function of merge-sort
async function merge(heightarray, l, m, r) {
    var n1 = m - l + 1;
    var n2 = r - m;
  
    var L = new Array(n1);
    var R = new Array(n2);
  
    for (var i = 0; i < n1; i++)
    {  await waitforme(2)//wait for 2 miliseconds
       L[i] = heightarray[l + i];
    }
    for (var j = 0; j < n2; j++)
     {
     await waitforme(2)//wait for 2 miliseconds
     R[j] = heightarray[m + 1 + j];
    }
    // Merging the arrays back into arr[l..r]
    var i = 0;
    var j = 0;
    // Initial index of merged subarray
    var k = l;
    await waitforme(2)//wait for 2 miliseconds
  
      while (i < n1 && j < n2) {
          await waitforme(2)//wait for 2 miliseconds
        if (L[i] <= R[j]) {
          heightarray[k] = L[i];
          document.getElementById(array_of_bars[k].id).style.height = `${L[i]}px`;
          document.getElementById(array_of_bars[k].id).style.borderLeft=`2px solid green`
          i++;
        } else {
          heightarray[k] = R[j];
          document.getElementById(array_of_bars[k].id).style.height = `${R[j]}px`;
          document.getElementById(array_of_bars[k].id).style.borderLeft=`2px solid green`
          j++;
        }
        k++;
      }
    
    // Copy the remaining elements of L[]
  
      while (i < n1) {
          await waitforme(2)//wait for 2 miliseconds
        heightarray[k] = L[i];
        document.getElementById(array_of_bars[k].id).style.height = `${L[i]}px`;
        document.getElementById(array_of_bars[k].id).style.borderLeft=`2px solid green`
        i++;
        k++;
      }
  
    // Copy the remaining elements of R[]
      while (j < n2) {
          await waitforme(2)//wait for 2 miliseconds
        heightarray[k] = R[j];
        document.getElementById(array_of_bars[k].id).style.height = `${R[j]}px`;
        document.getElementById(array_of_bars[k].id).style.borderLeft=`2px solid green`
        j++;
        k++;
      }
  }
  async function mergeSort(heightarray, l, r) {
    if (l >= r) {
      return; //returns recursively
    }
    var m = l + parseInt((r - l) / 2);
     await mergeSort(heightarray, l, m);//wait till promise is returned
     await mergeSort(heightarray, m + 1, r);//wait till promise is returned
    await merge(heightarray, l, m, r);//wait till promise is returned
  }