JS实现本地存储信息的方法(基于localStorage与userData)

<script type="text/javascript">
(function() {
  window.localData = {
    hname : location.hostname ? location.hostname : &#39;localStatus&#39;,
    isLocalStorage : window.localStorage ? true : false,
    dataDom : null,
    initDom : function() {
      if (!this.dataDom) {
        try {
          this.dataDom = document.createElement(&#39;input&#39;);
          this.dataDom.type = &#39;hidden&#39;;
          this.dataDom.style.display = "none";
          this.dataDom.addBehavior(&#39;#default#userData&#39;);
          document.body.appendChild(this.dataDom);
          var exDate = new Date();
          exDate = exDate.getDate() + 30;
          this.dataDom.expires = exDate.toUTCString();
        } catch (ex) {
          return false;
        }
      }
      return true;
    },
    set : function(key, value) {
      if (this.isLocalStorage) {
        window.localStorage.setItem(key, value);
      } else {
        if (this.initDom()) {
          this.dataDom.load(this.hname);
          this.dataDom.setAttribute(key, value);
          this.dataDom.save(this.hname)
        }
      }
    },
    get : function(key) {
      if (this.isLocalStorage) {
        return window.localStorage.getItem(key);
      } else {
        if (this.initDom()) {
          this.dataDom.load(this.hname);
          return this.dataDom.getAttribute(key);
        }
      }
    },
    remove : function(key) {
      if (this.isLocalStorage) {
        localStorage.removeItem(key);
      } else {
        if (this.initDom()) {
          this.dataDom.load(this.hname);
          this.dataDom.removeAttribute(key);
          this.dataDom.save(this.hname)
        }
      }
    }
  };
  var text = document.getElementById(&#39;localDataHook&#39;);
  var btn = document.getElementById(&#39;clearBtnHook&#39;);
  window.onbeforeunload = function() {
    localData.set(&#39;beiyuuData&#39;, text.value);
  };
  btn.onclick = function() {
    localData.remove(&#39;beiyuuData&#39;);
    text.value = &#39;&#39;
  };
  if (localData.get(&#39;beiyuuData&#39;)) {
    text.value = localData.get(&#39;beiyuuData&#39;);
  }
})();
</script>

window.onbeforeunload = function() {
  if (!canLeavePage()) {
    return ('确认离开当前页面吗？未保存的数据将会丢失！');
  }