sample.js

var select = function(){
	for(var i=1;i<=100;i++)
		if(!(location.pathname+i in window.localStorage))
			return location.pathname+i;
}

var category = "[" + document.getElementsByClassName("path btmPath")[0].getElementsByTagName("a")[2].getElementsByTagName("span")[0].innerHTML + "]";
var title = document.getElementById("titleBox").getElementsByTagName("h2")[0].innerHTML;
var price = document.getElementById("minPrice").getElementsByTagName("span")[0].innerHTML;
var obj = {category:category,title:title,price:price};
window.localStorage.setItem(select(),JSON.stringify(obj));

var str = "";
var sum = 0;
for(key in window.localStorage){
	if(key.search(/item/) >= 0){
		var obj2 = JSON.parse(window.localStorage.getItem(key));
		for(key2 in obj2){
			str += obj2[key2];
			str += " ";
			if(key2 == "price")
				sum += Number(obj2[key2].slice(1).replace(",",""));
		}
		str += "\n";
	}
}
str += "合計" + "   " + "\\" + String(sum).replace(/(\d)(?=(\d\d\d)+(?!\d))/g,'$1,');
alert(str);