function urlsafe(str){
	var len = 0;
	var result = '';
	var previous = '';
	var str_len = str.length;
	//if (str_len > 50) str_len = 50;
	var c = '';
	
	for (i = 0; i < str_len && len < 50; i++){
		c = strtolower(str.charAt(i));
		
		if(isalphanumeric(c)){
			result += c;
			previous = c;
			len++;
		} else {
			if (previous != '-'){
				result += '-';
				previous = '-';
				len++;
			}
		}
	}
	return result;
}

function strtolower(str){
	return (str+'').toLowerCase();
}

function substr(str,start,length){
	return str.substr(start,length);
}

function isalphanumeric(str){
	var re = /^[a-zA-Z_0-9]$/;
	if(re.test(str)){
		return true;
	}
}