Find prime numbers in an array - Javascript

arrayFilterPrime.js

var a = [5, 9, 63, 29, 35, 6, 55, 23]
var prime = [];

function isPrime(item) {
    var identifier = item / 2;
      for (var j = 2; j <= identifier; j++) {
       if ((item % j) == 0) { // modulous
        return false;
       } 
     }
     return true;
}
for (var index = 0; index < a.length; index++) {
  if (isPrime(a[index])) {
      prime.push(a[index])
  }
}

console.log(prime);