Pure Javascript - store object in cookie

Question

No jQuery.

I want to store an object or array in a cookie.

The object should be usable after page refresh.

How do I do that with pure JavaScript? I read many posts, but do not know how to serialize appropriately.

---

EDIT: Code:

var instances = {};
...
instances[strInstanceId] = { container: oContainer };
...
instances[strInstanceId].plugin = oPlugin;
...
JSON.stringify(instances); 
// throws error 'TypeError: Converting circular structure to JSON'

1. How do I serialize instances ?

2. How do I maintain functionality, but change structure of instance to be able to serialize with stringify ?

Answer 1

Try that one to write

function bake_cookie(name, value) {
  var cookie = [name, '=', JSON.stringify(value), '; domain=.', window.location.host.toString(), '; path=/;'].join('');
  document.cookie = cookie;
}

To read it take:

function read_cookie(name) {
 var result = document.cookie.match(new RegExp(name + '=([^;]+)'));
 result && (result = JSON.parse(result[1]));
 return result;
}

To delete it take:

function delete_cookie(name) {
  document.cookie = [name, '=; expires=Thu, 01-Jan-1970 00:00:01 GMT; path=/; domain=.', window.location.host.toString()].join('');
}

To serialize complex objects / instances, why not write a data dump function in your instance:

function userConstructor(name, street, city) {
   // ... your code
   this.dumpData = function() {
     return {
        'userConstructorUser': {
            name: this.name,
            street: this.street,
            city: this.city
         }
       }
    }

Then you dump the data, stringify it, write it to the cookie, and next time you want to use it just go:

  var mydata = JSON.parse(read_cookie('myinstances'));
  new userConstructor(mydata.name, mydata.street, mydata.city);

Answer 2

Use either object's own .toString() method if it gives meaningful serialization or JSON.stringify() . Do note, however, that cookies are usually limited in length and won't be able to hold big amounts of data.

Answer 3

A cookie adaptation class from : http://www.sitepoint.com/cookieless-javascript-session-variables/

All you need to do is to set and get variables you need to store in cookie.

Work with: int, string, array, list, Complex object

Exemple:

var toStore =  Session.get('toStore');

if (toStore == undefined)
    toStore = ['var','var','var','var'];
else
    console.log('Restored from cookies'+toStore);

Session.set('toStore', toStore);

Class:

// Cross reload saving
if (JSON && JSON.stringify && JSON.parse) var Session = Session || (function() {
// session store

var store = load();

function load()
{
    var name = "store";
    var result = document.cookie.match(new RegExp(name + '=([^;]+)'));

    if (result)
        return JSON.parse(result[1]);

    return {};
}

function Save() {
    var date = new Date();
    date.setHours(23,59,59,999);
    var expires = "expires=" + date.toGMTString();
    document.cookie = "store="+JSON.stringify(store)+"; "+expires;
};

// page unload event
if (window.addEventListener) window.addEventListener("unload", Save, false);
else if (window.attachEvent) window.attachEvent("onunload", Save);
else window.onunload = Save;

// public methods
return {

    // set a session variable
    set: function(name, value) {
        store[name] = value;
    },

    // get a session value
    get: function(name) {
        return (store[name] ? store[name] : undefined);
    },

    // clear session
    clear: function() { store = {}; }
};
})();

Answer 4

如果您可以将对象序列化为其规范字符串表示形式，并且可以从所述字符串表示形式将其反序列化为其对象形式，则可以将其放入cookie中。