Math: Get Factors of X

function factors( n ){
  var
    u = Math.floor( Math.sqrt( n ) ),
    i,
    f = [],
    e = [];

  for( i = 1 ; i <= u; i++ ) {
    if( n % i == 0 ) {
      f.push( i );
      e.unshift( n / i );
    }
  }
  if( e[ 0 ] == u ) e.shift();
  return f.concat( e );
}

Here the minimized version (147 bytes)...

function factors(n,u,i,f,e){for(u=Math.sqrt(n)|0,i=1,e=[],f=[];i<=u;i++)if(n%i<1){f.push(i);e.unshift(n/i)}if(e[0]==u)e.shift();return f.concat(e)}