MergeSort

function merge(arr1,arr2){
    let result = [];
    let i=0;
    let j=0;
    while(i<arr1.length&&j<arr2.length){
        console.log('i='+i+''+'j='+j);

        
        if(arr2[j]>arr1[i]){
            result.push(arr1[i]);
            i++;
            console.log(result);
        }else{
            result.push(arr2[j]);
            j++;
          console.log(result);
        }
        
       
    }
     while(i<arr1.length){
            result.push(arr1[i]);
       i++;
        }
        
        while(j<arr2.length){
            result.push(arr2[j]);
          j++;
        }
    return result;
    
}


function mergeSort(arr){
    if(arr.length<=1) return arr;
    let mid = Math.floor(arr.length/2);
    let left = mergeSort(arr.slice(0,mid));
    let right = mergeSort(arr.slice(mid));
    return merge(left,right);
}

console.log(mergeSort([5,60,1,20,3,44,21]));