JavaScript code to check for prime numbers

Took 10 minutes and 16 seconds to code JavaScript prototype to check for prime numbers. Here is the code snippet.

Code (Run Code):

function checkPrime(num) {

if (num == 1) {

return num + ' is not a prime number and not a composite number';

} else if (num == 2) {

return num + ' is a prime number';

}

for (var x = 2; x < num; x++) {

if (num % x == 0) {

return num + ' is not a prime number';

}

}

return num + ' is a prime number';

}

function main(){

document.getElementById("result").innerHTML =

checkPrime(document.getElementById("num").value);

}