find_prime.js

function isPrime(num) {
    for ( var i = 2; i < num; i++ ) {
        if ( num % i === 0 ) {
            return false;
        }
    }
    return true;
}

y = 2
x=confirm("Find the first prime number?")
while (x) {
    if (y===2) {
        alert("it is "+y)
        y++
        x=confirm("Find the next prime number?")
    } else {
        if (isPrime(y)) {
            alert("it is "+y)
            x=confirm("Find the next prime number?")
        }
        y++
    }
}