Prime numbers

function prime(input){

    let upper=Number(input.shift());

    for (var counter = 2; counter <= upper; counter++)  {
        let isPrime = true;

        for (var div = 2; div <counter; div++) {

            if (counter % div === 0) {
                isPrime=false;}
        }

        if (isPrime==true) {
        console.log(counter);}
    }
}