Jstorage类库本地存储数据

　　jStorage使用 HTML5 local storage 作为存储容器或者不支持local storage时（IE7-）则使用 userData behavior 作为存储容器。

　　对于IE浏览器，存储的数据位置为

userData

　　在XP下，一般位于C:\Documents and Settings\用户名\UserData，有些时候会在C: \Documents and Settings\用户名\Application Data\Microsoft\Internet Explorer \UserData。

　　在Vista下，位于C:\Users\用户名\AppData\Roaming\Microsoft\Internet Explorer\UserData。

local storage，不同浏览器位置不一样，一般是在浏览器安装目录或者当前登录系统系统的账户Documents and Settings配置里面

• chrome：C:/Documents and Settings/UserName/Local Settings/Application Data/Google/Chrome/User Data/Default/Local Storage
• firefox：C:\Documents and Settings\Administrator\Application Data\Mozilla\Firefox\Profiles\7ri7n2cn.default，为当前启动firefox的配置文件夹，此文件夹下有个localstore.rdf文件。

来源：http://www.jstorage.info/

jStorage使用方法和API

jStorage requires Prototype, MooTools or jQuery + jQuery-JSON or JSON2. Either way, the syntax stays the same.

Simple setup to support jStorage with JSON2

<script src="//cdnjs.cloudflare.com/ajax/libs/json2/20110223/json2.js"></script>
<script src="https://raw.github.com/andris9/jStorage/master/jstorage.js"></script>
<script> /* $.jStorage is now available */ </script>

Setup with jQuery2

<script src="//cdnjs.cloudflare.com/ajax/libs/json2/20110223/json2.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/1.8.0/jquery.min.js"></script>
<script src="https://raw.github.com/andris9/jStorage/master/jstorage.js"></script>
<script> /* $.jStorage is now available */ </script>

6. Function reference

set(key, value[, options])

$.jStorage.set(key, value, options)

Saves a value to local storage. key needs to be string otherwise an exception is thrown. value can be any JSONeable value, including objects and arrays or a XML node.
Currently XML nodes can't be nested inside other objects: $.jStorage.set("xml", xml_node) is OK but $.jStorage.set("xml", {xml: xml_node}) is not.

Options is an optional options object. Currently only available option is options.TTL which can be used to set the TTL value to the key ($.jStorage.set(key, value, {TTL: 1000});). NB - if no TTL option value has been set, any currently used TTL value for the key will be removed.

get(key[, default])

value = $.jStorage.get(key)
value = $.jStorage.get(key, "default value")
    

get retrieves the value if key exists, or default if it doesn't. key needs to be string otherwise an exception is thrown. default can be any value.

deleteKey(key)

$.jStorage.deleteKey(key)

Removes a key from the storage. key needs to be string otherwise an exception is thrown.

setTTL(key, ttl)

$.jStorage.set("mykey", "keyvalue");
$.jStorage.setTTL("mykey", 3000); // expires in 3 seconds

Sets a TTL (in milliseconds) for an existing key. Use 0 or negative value to clear TTL.

getTTL(key)

ttl = $.jStorage.getTTL("mykey"); // TTL in milliseconds or 0

Gets remaining TTL (in milliseconds) for a key or 0 if not TTL has been set.

flush()

$.jStorage.flush()

Clears the cache.

index()

$.jStorage.index()

Returns all the keys currently in use as an array.

var index = $.jStorage.index();
console.log(index); // ["key1","key2","key3"]

storageSize()

$.jStorage.storageSize()

Returns the size of the stored data in bytes

currentBackend()

$.jStorage.currentBackend()

Returns the storage engine currently in use or false if none

reInit()

$.jStorage.reInit()

Reloads the data from browser storage

storageAvailable()

$.jStorage.storageAvailable()

Returns true if storage is available

subscribe(channel, callback)

$.jStorage.subscribe("ch1", function(channel, payload){
    console.log(payload+ " from " + channel);
});

Subscribes to a Publish/Subscribe channel)

publish(channel, payload)

$.jStorage.publish("ch1", "data");

Publishes payload to a Publish/Subscribe channel

listenKeyChange(key, callback)

$.jStorage.listenKeyChange("mykey", function(key, action){
    console.log(key + " has been " + action);
});

Listens for updates for selected key. NB! even updates made in other windows/tabs are reflected, so this feature can also be used for some kind of publish/subscribe service.

stopListening(key[, callback])

$.jStorage.stopListening("mykey"); // cancel all listeners for "mykey" change

Stops listening for key change. If callback is set, only the used callback will be cleared, otherwise all listeners will be dropped.

7. Usage example

jQuery

jQuery doesn't come with built in JSON encoder/decoder so if you need to support IE6/IE7 you should include one yourselt like in the example

<script src="//cdnjs.cloudflare.com/ajax/libs/json2/20110223/json2.js"></script>
<script src="//code.jquery.com/jquery-1.9.1.min.js"></script>
<script src="jstorage.js"></script>
<script>
// Check if "key" exists in the storage
var value = $.jStorage.get("key");
if(!value){
    // if not - load the data from the server
    value = load_data_from_server()
    // and save it
    $.jStorage.set("key",value);
}
</script>

Prototype

<script src="//ajax.googleapis.com/ajax/libs/prototype/1.7.1.0/prototype.js"></script>
<script src="jstorage.js"></script>
<script>
// Check if "key" exists in the storage
var value = $.jStorage.get("key");
if(!value){
    // if not - load the data from the server
    value = load_data_from_server()
    // and save it
    $.jStorage.set("key",value);
}
</script>

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