JavaScript: find prime numbers

first100primeNumbers.js

var arr = [];
var x = 0;
while(arr.length < 100){
    if(isPrime(x)) { arr.push(x); }
    x++;
}

console.log(arr);
console.log(arr.length)

isPrime.js

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

primeNumbsLowerThan100.js

var arr = [];
for(var i = 0; i < 100; i++){
    if(isPrime(i)) { arr.push(i); }
}
console.log(arr);
console.log(arr.length);