hashchange实现ajax无刷新回退

<div id="nihao"></div>
<button>change</button>

var i=0, url;

var show = function(num) {
if (num == 0) {
url = "data/data_1.json";
} else if (num == 1) {
url = "data/data_2.json";
}
$.get(url,{"cache":false}, function(result) {
$("#nihao").text(result.code);
},"json");
};

if(window.attachEvent) {
window.attachEvent("onhashchange", function(e) {
var hash = parseInt(window.location.hash.substring(1,2), 10);
show(hash);
});
} else if(window.addEventListener) {
window.addEventListener("hashchange",function(e) {
var hash = parseInt(window.location.hash.substring(1,2), 10);
show(hash);
}, false);
}

$("button").click(function() {

if(i == 1) {
window.location.hash = i--;
} else if(i == 0) {
window.location.hash = i++;
}
});