var cache = {
"uuid1": { // DOM節(jié)點1緩存數(shù)據(jù)，"uuid1"相當(dāng)于dom1[expando]
"name1": value1,
"name2": value2
},
"uuid2": { // DOM節(jié)點2緩存數(shù)據(jù)，“uuid2"相當(dāng)于dom2[expando]
"name1": value1,
"name2": value2
}
// ......
};

(function(window, undefined) {
var cacheData = {}, // 用來存儲數(shù)據(jù)的對象
win = window, // 把window緩存給一個變量
uuid = 0,
// 聲明隨機數(shù)(8位)
// 注意+new Date()生成的隨機數(shù)是Number類型，與一個空字符串連接后(或使用toString方法轉(zhuǎn)型后)變成字符串，才可使用slice方法。
expando = "cacheData" + (+new Date() + "").slice(-8);
// (+new Date()).toString().slice(-8)等價于expando
// 寫入緩存
var data = function(elem, name, value) {
// 或使用原生方法驗證字符串Object.prototype.toString.call(elem) === "[object String]"
// 如果elem為字符串
if (typeof elem === "string") {
// 如果傳入name參數(shù)，則為寫入緩存
if (name !== undefined) {
cacheData[elem] = name;
}
// 返回緩存數(shù)據(jù)
return cacheData[elem];
// 如果elem為DOM節(jié)點
} else if (typeof elem === "object") {
var id,
thisCache;
// 如果elem不存在expando屬性，則添加一個expando屬性(第一次給元素設(shè)置緩存)，否則直接獲取已有的expando和id值
if (!elem[expando]) {
id = elem[expando] = ++uuid;
thisCache = cacheData[id] = {};
} else {
id = elem[expando];
thisCache = cacheData[id];
}
// 把一個隨機數(shù)作為當(dāng)前緩存對象的一個屬性，利用該隨機數(shù)就能找到該緩存對象
if (!thisCache[expando]) {
thisCache[expando] = {};
}
if (value !== undefined) {
// 將數(shù)據(jù)存到緩存對象中
thisCache[expando][name] = value;
}
// 返回DOM元素存儲的數(shù)據(jù)
return thisCache[expando][name];
}
};
// 刪除緩存
var removeData = function(elem, name) {
// 如果elem為字符串，則直接刪除該屬性值
if (typeof elem === "string") {
delete cacheData[elem];
// 如果key為DOM節(jié)點
} else if (typeof elem === "object") {
// 如果elem不存在expando屬性，則終止執(zhí)行，不用刪除緩存
if (!elem[expando]) {
return;
}
// 檢測對象是否為空
var isEmptyObject = function(obj) {
var name;
for (name in obj) {
return false;
}
return true;
}
removeAttr = function() {
try {
// IE8即標(biāo)準(zhǔn)瀏覽器可以直接使用delete來刪除屬性
delete elem[expando];
} catch (e) {
// IE6/IE7使用removeAttribute方法來刪除屬性
elem.removeAttribute(expando);
}
},
id = elem[expando];
if (name) {
// 只刪除指定的數(shù)據(jù)
delete cacheData[id][expando][name];
// 如果是空對象，id所對應(yīng)的數(shù)據(jù)對象全部刪除
if (isEmptyObject(cacheData[id][expando])) {
delete cacheData[id];
removeAttr();
}
} else {
// 刪除DOM元素存到緩存中的所有數(shù)據(jù)
delete cacheData[id];
removeAttr();
}
}
};
// 把data和removeData掛在window全局對象下，這樣在外部也能訪問到這兩個函數(shù)
win.expando = expando;
win.data = data;
win.removeData = removeData;
})(window, undefined);

<div id="demo" style="height: 100px; width: 100px; background: #ccc; color: #fff; margin: 20px; text-align: center; line-height: 100px;">
demo
</div>

window.onload = function() {
// 測試
var demo = document.getElementById("demo");
// 寫入緩存
data(demo, "myName", "hcy");
console.log(data(demo, "myName")); // hcy
data(demo, "myBlog", "http://www.cnblogs.com/cyStyle");
console.log(data(demo, "myBlog")); // http://www.cnblogs.com/cyStyle
// 刪除DOM元素的某個緩存值
removeData(demo, "myBlog");
console.log(data(demo, "myBlog")); // undefined
console.log(data(demo, "myName")); // hcy
console.log(demo[expando]); // 1
// 刪除DOM元素
removeData(demo);
console.log(demo[expando]); // undefined
};