从本地存储检索数据时如何将数据转换为不同类型

Question

我正在编写一个小库来操作 localStorage 中的数据。

下面是代码片段：

function AppStorage (appName) {
    "use strict";

    var prefix  = appName;

    var saveItem = function (key, value) {

        if (!key || !value) {

            console.error("Missing parameters \"key\" and \"value\"");    

            return false;
        }

        if (window.localStorage && window['localStorage']) {

            try {
                if (typeof value === 'Object') localStorage.setItem(prefix + '_' + key, JSON.stringify(value));
                if (typeof value === 'string') localStorage.setItem(prefix + '_' + key, value);

                return true;

            } catch (e) {

                return false;

            }

        } else  {

            return false;

        }

    }

    var getItem = function (key) {

        if (!key) {

            console.error("Missing parameter \"key\"");    

            return false;
        }

        if (window.localStorage && window['localStorage']) {
            try {

                return localStorage.getItem(prefix + '_' + key);                

            } catch (e) {

                return false;

            }

        } else  {

            return false;

        }

    }

    var removeItem = function (key) {

        if (!key) {

            console.error("Missing parameter \"key\"");

            return false;
        }

        if (window.localStorage && window['localStorage']) {

            try {
                localStorage.removeItem(prefix + '_' + key);
                return true;

            } catch (e) {
                return false;
            }

        } else  {

            console.log("Browser does not support HTML5 Web Storage");

        }

    }

    return {
        set: function (key, value) {
            return saveItem(key, value);
        },
        get: function (key) {
            return getItem(key);
        },
        remove: function (key) {
            return removeItem(key);
        }
    }

}

var as = new AppStorage ('MyApp');

我怎么会遇到以下两个问题。

1) 当通过 get() 检索数据时，存储的信息作为 string 返回。我需要在传递之前以相同的格式接收此信息。

2) 能否进一步改进以下代码片段。

Answer 1

希望有所帮助！

var ClientStorageService = (function(persistent, session) {
  if(!persistent && !session) {
    throw new Error('ClientStorage Not Suppoerted'); 
  }

  function ClientStorage() {};

  ClientStorage.prototype.driver = persistent || session;
  ClientStorage.prototype.prefix = 'HELLOWORLD_';
  
  ClientStorage.prototype.usePersistent = function() {
    if(persistent) {
      this.driver = persistent;
      return true;
    }
    
    return false;
  };
  ClientStorage.prototype.useSession = function() {
  if(session) {
      this.driver = session;
      return true;
    }
    
    return false;
  };

  ClientStorage.prototype.read = function(key) {
    key = this.prefix + key;
    var data = this.driver.getItem(key);
    
    if(data) {
      
      try {
        data = JSON.parse(data);
      } catch(e) {}
      
      return data;
    }
    
    return null;
  };
  
  ClientStorage.prototype.store = function(key, val) {
    key = this.prefix + key.toString();
    
    try {
      val = JSON.stringify(val);
    } catch(e) {}
    
    this.driver.setItem(key, val);
    
    return this;
  };
  
  ClientStorage.prototype.clear = function(key) {
    var task = 'clear';
    
    if(key) {
      key = this.prefix + key;
      task = 'removeItem';
    }
    
    this.driver[task](key);
  };

  return new ClientStorage();
})(window.localStorage, window.sessionStorage);

ClientStorageService.store('FOO', { greetings: 'Hello World' });
var result = ClientStorageService.read('FOO');

console.log('result is', result);

从本地存储检索数据时如何将数据转换为不同类型

How to convert the data into different types when retrieving from local storage

html

javascript

json

local-storage

web-storage