Counting specific digits used in squares of numbers using JavaScript

Problem

We are required to write a JavaScript function that takes in an integer n (n >= 0) and a digit d (0 <= d <= 9)

Our function should square all numbers k (0 <= k <= n) between 0 and n and count the numbers of digits d used in the writing of all the k**2.

Example

Following is the code −

const n = 25;
const d = 1;
const countDigits = (n, d) => {
   let k = 0, count = 0;
   d = d.toString();
   while (k <= n) {
      let a = 0;
      let s = (k*k).toString();
      for(let i = 0; i < s.length; i++)
         if(s[i] == d)
      a++;
      if (a > 0) {
         count += a;
      };
      k++;
   };
   return count;
};
console.log(countDigits(n, d));

Output

11