Write a JavaScript program to check prime number

Description: Check whether the numbers 2, 15, 17 and 1 are prime.

Hint:

• A prime number is greater than 1 and has no divisor other than 1 and itself.
• Test divisors up to the square root.

---

JavaScript prime number program

function isPrime(n) {
  if (n < 2) return false;
  for (let i = 2; i <= Math.sqrt(n); i++) {
    if (n % i === 0) return false;
  }
  return true;
}

for (const n of [2, 15, 17, 1]) {
  console.log(n + (isPrime(n) ? " is prime" : " is not prime"));
}

Output:

How it works

• Numbers below 2 are not prime.
• For 15 the loop finds that 15 % 3 === 0 and returns false.
• As soon as one divisor is found, the function returns.

• Previous Exercise
• Next Exercise

---

Tutorials
No Content Found.

Exercises & Assignments
No Content Found.

Interview Questions & Answers
No Content Found.