JavaScript program to check prime number or not

Following program shows you how to check a number is Prime or not.

function isPrime(n) {

	if (n === 1) {
		return false;
	} else if (n === 2) {
		return true;
	} else {
		for (var x = 2; x < n; x++) {
			if (n % x === 0) {
				return false;
			}
		}
		return true;
	}
}

console.log(isPrime(21));

Output:

false

Try it Online here https://onecompiler.com/javascript/3x5qdb7ge