function indexed( x, separator ) {
	var out;
	var N;
	var v;
	var i;

	N = x.length - 1;
	out = '';
	for ( i = 0; i <= N; i++ ) {
		v = x[ i ];
		if ( !isUndefinedOrNull( v ) ) {
			out += String( v );
		}
		if ( i < N ) {
			out += separator;
		}
	}
	return out;
}
Returns a string created by manually joining array elements using a specified separator.

@private
@param {Object} x - input array object
@param {integer} separator - separator
@returns {string} output string

@example
var x = [ 1, 2, 3, 4 ];

var out = indexed( x, ',' );
// returns '1,2,3,4'