javascript: indesign join string page number with symbol

gistfile1

function join_page_string (pages, symbol_first, symbol_last) {
	var page_string  = "";
	if( pages.length === 1 ) { return pages.toString();}
	for (var i = 0, len = pages.length; i < len; i++) {
		if(i < len-1) {				
			page_string += pages[i];
			if( i != len-2 ) { page_string += symbol_first}
		}else {			
			page_string += (symbol_last + pages[i]);			
		};			
	};
	return page_string;
};