Cómo fusionar dos matrices ordenadas en JavaScript

// using for single for loop 

let arrrone = [0,3,4,31];
let arrayTwo = [4,6,30,31,33];
let j = 0;
let k = 0;
let mergedArray = [];

let length = arrrone.length + arrayTwo.length;

console.log(length)

for(let i = 0; i<= length - 1; i++){
  if(arrrone[j] < arrayTwo[k]){
    mergedArray.push(arrrone[j]);
    j++;
  }
  else if(arrrone[j] > arrayTwo[k]){
    mergedArray.push(arrayTwo[k]);
    k++;
  }
  else if(arrrone[j] == arrayTwo[k]){
    mergedArray.push(arrrone[j]);
    mergedArray.push(arrayTwo[k]);
    j++;
    k++;
  }
}

console.log(mergedArray)
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