How to get the numbers which can divide all values in an array - JavaScript

We are required to write a JavaScript function that takes in an array of numbers and returns a number which can exactly divide all the numbers in the array.

Let’s say the following is our array −

const arr = [4, 6, 34, 76, 78, 44, 34, 26, 88, 76, 42];

Example

Following is the code −

const arr = [4, 6, 34, 76, 78, 44, 34, 26, 88, 76, 42];
const dividesAll = el => {
   const result = [];
   let num;
   for (num = Math.floor(el / 2); num > 1; num--){
      if (el % num === 0) {
         result.push(num);
      }
   };
   return result;
};
const dividesArray = arr => {
   return arr.map(dividesAll).reduce((acc, val) => {
      return acc.filter(el => val.includes(el));
   });
};
console.log(dividesArray(arr));

Output

This will produce the following output in console −

[ 2 ]