本地存储组件--兼容IE低版本

在前端开发过程中，会用到本地缓存，但是由于浏览器对不同规范支持的程度不一样，每次进行使用都要为兼容行花费不少时间。我整理了一个本地存储的组件。

组件特点：

可以配置使用localStorage、sessionStorage、cookie、Object，IE低版本支持userData
统一的使用接口set、get、remove
使用方便，直接引入JS，进行初始化即可

下面是源码:

(function() {
    var ua = navigator.userAgent.toLowerCase();
    var t = ua.match(/msie ([d.]+)/);
    var ie = t && t[1];
    var useUserData = ie ==6 || ie == 7;
  
    var encodeVal = function(value) {
        return encodeURIComponent(value);
        };
  
    var decodeVal = function(value) {
        return decodeURIComponent(value);
        };
  
    var isCookieEnabled = function() {
        if(window.navigator.cookieEnabled) {
            return window.navigator.cookieEnabled;
        }
        var key = 'test_cookie_enable',
                value = 'test' + Math.random(),
                result = _cookieStorage.set(key, value);
        if (!result) {
            return false;
        }
        var value2 = _cookieStorage.get(key);
        _cookieStorage.remove(key);
        return value == value2;
    };
  
    var _sessionStorage = {
            get : function(key) {
                return sessionStorage.getItem(key) || null;
            },
  
            set : function(key, value) {
                sessionStorage.setItem(key, value);
            },
  
            remove : function(key) {
                sessionStorage.removeItem(key);
            }
        };
  
    var _localStorage = {
            get : function(key) {
                return decodeVal(localStorage.getItem(key)) || null;
            },
  
            set : function(key, value) {
                value = encodeVal(value);
                localStorage.setItem(key, value);
            },
  
            remove : function(key) {
                localStorage.removeItem(key);
            }
        };
  
    var _userDataStorage = {
            init: function(maxage) {
                var memory = document.createElement('input');
                this.memory = memory;
                memory.style.display = "none";
                memory.style.behavior = "url('#default#userData')";
                document.body.appendChild(memory);
  
                if(maxage) {
                    var now = +new Date();
                    var expires = now + maxage * 1000;
                    memory.expires = new Date(expires).toUTCString();
                }
  
                memory.load('UserDataStorage');
            },
  
            get : function (key) {
                return decodeVal(this.memory.getAttribute(key)) || null;
            },
  
            set : function(key, value) {
                value = encodeVal(value);
                this.memory.setAttribute(key, value);
                this.memory.save('UserDataStorage');
            },
  
            remove : function(key) {
                this.memory.removeAttribute(key);
                this.memory.save('_userDataStorage');
            }
        };
  
    var _cookieStorage = {
            init: function(maxage, path) {
                this.maxage = maxage;
                this.path = path;
            },
            set : function(key, value) {
                var cookie = key + '=' + encodeVal(value);
                if(this.maxage) cookie += '; max-age=' + this.maxage;
                if(this.path) cookie += '; path=' + this.path;
                document.cookie = cookie;
            },
  
            get : function(key) {
                var cookies = document.cookie;
                var reg = new RegExp('(?:^ |)(' + key + ')=([^;]+)');
                var value = cookies.match(reg);
                if(value) {
                    return decodeVal(value[2]);
                }
                return null
            },
  
            remove : function(key) {
                this.init(0, '/');
                this.set(key, '');
            }
        };
  
    var _objectStorage = {
        init : function() {
            this.data = {};
        },
        set : function(key, value) {
            value = encodeVal(value);
            this.data[key] = value;
        },
        get : function (key) {
            return decodeVal(this.data[key]) || null;
        },
        remove : function(key) {
            delete this.data[key];
        }
    };
  
    /**
     * 本地存储
     * @param {String} type 存储类型 [local,session,cookie,page]
     * @param {Number} maxage cookie到期时间 单位秒
     * @param {String} path 路径
     * @return {Object} 具有set、get、remove方法
     */
    function Storage(type, maxage, path) {
        var storage;
        maxage = maxage || '';
        path = path || '/';
        type = type || 'local';
  
        switch (type) {
            case 'local' :
                try { // 禁用cookie、localStorage时访问会报错
                    storage = window.localStorage ? _localStorage : useUserData ? _userDataStorage : Object;
                } catch (e) {
                    storage = _objectStorage;
                }
                break;
            case 'session' :
                try { // 禁用cookie、_localStorage时访问会报错
                    storage = window.sessionStorage ? _sessionStorage : _objectStorage;
                } catch (e) {
                    storage = _objectStorage;
                }
                break;
            case 'cookie' :
                storage = isCookieEnabled() ? _cookieStorage : _objectStorage;
                break;
            case 'page' :
                storage = _objectStorage;
        }
        storage.init && storage.init(maxage, path);
        return storage;
    }
  
    window.Storage = Storage;
})();

　　使用例子：

var storage = new Storage('local');
    storage.set('name', '中国人');
    var name = storage.get('name');
    alert(name);
    storage.remove('name');
    var name = storage.get('name');
    alert(name);

　　如果觉得有用可以推荐一下，那里实现的有问题，也希望指正。