Sieve of Eratosthenes in JavaScript

Sieve.js

/*
Sample Implementation of Sieve algorithm for 1-3000
not optimized yet
*/
var ar = [];
var max = 3000;
//loop should run only till the square root of the maximum
var maxloop = Math.round(Math.sqrt(max));
for(a=0;a<max;a++){
    ar.push(true);
}
function isPrime(n){
  	if(!n || n==1)
      return false;
	var end = Math.floor(Math.sqrt(n));
  	//console.log(end);
  	for(i=2;i<end;i++){
    	if(n%i==0)
          return false;
    }
  //console.log(n)
  return true;
}
for(j=0;j<=maxloop;j++){
	if(ar[j]){
    	if(isPrime(j)){
        	for(x=(j+j);x<max;x+=j){
            	ar[x]=false;
            }
        }
      else{
      ar[j]=false;
      }
    }
}

ar.filter(function(n,i){
	n && console.log(i)
})