Question

It has to be with just functions, variables, loops, etc (Basic stuff). I’m having trouble coming up with the code from scratch from what I’ve I learned so far(Should be able to do it). Makes me really mad :/. If you could give me step by step to make sure I understand I’d really really appreciated. Thanks a bunch in advanced.

How could I get the same result with a simpler code than this one:

var primes=4; 
for (var counter = 2; counter <= 100; counter = counter + 1)
{
    var isPrime = 0;
    if(isPrime === 0){ 
        if(counter === 2){console.log(counter);} 
        else if(counter === 3){console.log(counter);} 
        else if(counter === 5){console.log(counter);} 
        else if(counter === 7){console.log(counter);} 
        else if(counter % 2 === 0){isPrime=0;} 
        else if(counter % 3 === 0){isPrime=0;} 
        else if(counter % 5 === 0){isPrime=0;} 
        else if(counter % 7 === 0){isPrime=0;}
        else {
            console.log(counter);
            primes = primes + 1;
        }
    }
}
console.log("Counted: "+primes+" primes");

Answer 1

This finds all prime numbers between 2 and 100:

var primes=0; 
var isprime = true;
for (var counter = 2; counter <= 100; counter = counter + 1)
{
    // For now, we believe that it is a prime
    isprime = true;
    var limit = Math.round(Math.sqrt(counter)); // See comment from @AresAvatar, below
    // We try to find a number between 2 and limit that gives us a reminder of 0
    for (var mod = 2; mod <= limit; mod++) {
        // If we find one, we know it's not a prime
        if (counter%mod == 0) {
            isprime = false;
            break; // Break out of the inner for loop
        }
    }

    if (isprime) {
        console.log(counter, limit);
        primes = primes + 1;
    }
}
console.log("Counted: "+primes+" primes");