prime number function js

1// This seems to be the most common and comprehensive means
2// of implementing a 'is a number a prime function' in javascript 
3// if you would like t0 learn more complex , but efficient algorithms. 
4// Visit the link below
5// https://stackoverflow.com/questions/11966520/how-to-find-prime-numbers-between-0-100
6
7function isPrime(num) {
8  if(num < 2) return false;
9
10  for (let k = 2; k < num; k++){
11    if( num % k == 0){
12      return false;
13    }
14  }
15  return true;
16}

1// program to check if a number is prime or not
2function isPrime(){
3    // take input from the user
4    const number = parseInt(prompt("Enter a positive number: "));
5    let isPrime = true;
6
7    // check if number is equal to 1
8    if (number === 1) {
9        console.log("1 is neither prime nor composite number.");
10    }
11
12    // check if number is greater than 1
13    else if (number > 1) {
14
15        // looping through 2 to number-1
16        for (let i = 2; i < number; i++) {
17            if (number % i == 0) {
18                isPrime = false;
19                break;
20            }
21        }
22
23        if (isPrime) {
24            console.log(`${number} is a prime number`);
25        } else {
26            console.log(`${number} is a not prime number`);
27        }
28    }
29
30    // check if number is less than 1
31    else {
32        console.log("The number is not a prime number.");
33    }
34}