localStorage的使用和封装

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(function(window,localStorage,undefined){
var LS = {
    set : function(key, value){
        //在iPhone/iPad上有时设置setItem()时会出现诡异的QUOTA_EXCEEDED_ERR错误
        //这时一般在setItem之前，先removeItem()就ok了
        if( this.get(key) !== null )
            this.remove(key);
        localStorage.setItem(key, value);
    },
    //查询不存在的key时，有的浏览器返回undefined，这里统一返回null
    get : function(key){
        var v = localStorage.getItem(key);
        return v === undefined ? null : v;
    },
    remove : function(key){ localStorage.removeItem(key); },
    clear : function(){ localStorage.clear(); },
    each : function(fn){
        var n = localStorage.length, i = 0, fn = fn || function(){}, key;
        for(; i 
  
 
 
  
var LocalData = {  
    hname:location.hostname?location.hostname:'localStatus',
    isLocalStorage:window.localStorage?true:false,
    dataDom:null,

    initDom:function(){ //初始化userData
        if(!this.dataDom){
            try{
                this.dataDom = document.createElement('input');//这里使用hidden的input元素
                this.dataDom.type = 'hidden';
                this.dataDom.style.display = "none";
                this.dataDom.addBehavior('#default#userData');//这是userData的语法
                document.body.appendChild(this.dataDom);
                var exDate = new Date();
                exDate = exDate.getDate()+30;
                this.dataDom.expires = exDate.toUTCString();//设定过期时间
            }catch(ex){
                return false;
            }
        }
        return true;
    },
    set:function(key,value){
        if(this.isLocalStorage){
            if( this.get(key) !== null )  
            	this.remove(key);  
            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){
        	var v = window.localStorage.getItem(key);  
	        return v === undefined ? null : v;
        }else{
            if(this.initDom()){
                this.dataDom.load(this.hname);
                return this.dataDom.getAttribute(key);
            }
        }
    },
    remove:function(key){
        if(this.isLocalStorage){
            window.localStorage.removeItem(key);
        }else{
            if(this.initDom()){
                this.dataDom.load(this.hname);
                this.dataDom.removeAttribute(key);
                this.dataDom.save(this.hname)
            }
        }
    } 
}