Recursive implementation of the Sieve of Eratosthenes algorithm for filtering a set of numbers for prime numbers.

JS Sieve of Eratosthenes

var sieve = function(xs) {
    var head = xs[0],
        tail = xs.slice(1);
    
    if(head === undefined) return [];
    
    if(head < 2) return sieve(tail);
        
    tail = tail.filter(function(x) { 
        return x % head > 0 ? true : false;
    });
    
    return [head].concat( sieve(tail) );
};