Implementing Priority Sort in JavaScript

We are required to write a JavaScript function that takes in two arrays of numbers, second being smaller in size than the first.

Our function should be a sorted version of the first array (say in increasing order) but put all the elements that are common in both arrays to the front.

For example − If the two arrays are −

const arr1 = [5, 4, 3, 2, 1];
const arr2 = [2, 3];

Then the output should be −

const output = [2, 3, 1, 4, 5];

Example

Following is the code −

const arr1 = [5, 4, 3, 2, 1];
const arr2 = [2, 3];
// helper function
const sorter = (a, b, arr) => {
   if(arr.includes(a)){
      return -1;
   };
   if(arr.includes(b)){
      return 1;
   };
   return a - b;
};
const prioritySort = (arr1, arr2) => {
   arr1.sort((a, b) => sorter(a, b, arr2));
};
prioritySort(arr1, arr2);
console.log(arr1);

Output

Following is the output in the console −

[ 2, 3, 1, 4, 5 ]