Develop Reference

Polymer, observe global var

I have a multiple custom elements that share the same list of data.
I'm trying to fire an event when the global list is changed.
The folowing code is working on FF and Safari, but not on Chrome.
Any suggestion for the issue, or maybe a better way to do it?
Thanks,
(function() {
var _list = null;
Polymer("dmw-datatypes", {
ready:function(){
...retreiving a list async...
},
get list() {
return _list;
},
listReceived: function(json) {
_list=json;
},
listChanged: function(oldValue, newValue) {
this.fire('list-received');
}
});
})();

This sounds like a symptom of the fact that Object.observe() (which is native in Chrome) doesn't work out-of-the-box with computed properties (like your get list() {}). The other browsers use manual dirty-checking to polyfill this behavior, so they work fine. Basically, you're going to need to create your own Object.observe() notifier
var notifier = Object.getNotifier(this);
and notify observers when you update _list using notifier.notify(). The above link gives an example of this.

Retrieving data from browser local storage after saving it using javascript

In my backbone application, I am saving objects into local storage and only want to retrieve them once they are saved.
I tried using callback function (which fires after the function which saves data) but there is a bit of latency I observed and it returns undefined.
However, when I delay the function call (which retrieves the data) by 200 ms using setTimeout, it works just fine.
Is there an elegant way of doing it?
function delayed(){
// this callback function retrieves the data
callback.call(self);
}
window.setTimeout(delayed, 200);

So you can make a custom wrapper for this purpose:
(function() {
var Store = function() {
};
Store.prototype.set = function(key, value) {
localStorage.setItem(key, value);
return this.get(key);
};
Store.prototype.get = function(key) {
return localStorage.getItem(key);
};
var store = new Store();
console.log(store.set('foo', 'bar'));
})();
Fiddle

You could keep a duplicate outside of localStorage, in memory. You wouldn't need to rely localStorage's timing. Just write to localStorage often, and only load from it upon page load.
Just an idea! Without more specifics, it's hard to give a more concrete answer.

At first I thought of using the storage-event, but as you can see of this question - and this question, and this demonstration at html5demos.com, the use of the storage event is intended to track changes of the localstorage between windows / tabs, not inside the document itself.
But you can create your own event, firing when setItem is called by overriding setItem :
//create an "onstoragechange" custom event
var storageEvent = document.createEvent('Event');
storageEvent.initEvent('onstoragechanged', true, true);
document.addEventListener('onstoragechanged', function (e) {
alert('value added to localstorage');
//or
alert(localStorage.getItem('test'));
//call the code here, as you above would do after setTimeout
//"callback.call(self);" or whatever
}, false);
//override localStorage.setItem
var oldSetItem = Storage.prototype.setItem;
Storage.prototype.setItem = function() {
oldSetItem.apply(this, arguments);
document.dispatchEvent(storageEvent);
}
//test
localStorage.setItem('test', 'value');
demo / jsfiddle : http://jsfiddle.net/cYLHT/
Now you have an event that is dispatched each time you save anything to localStorage, and the written value actually is present. Expand this with events that helps out your application - like a special event if a certain important key is updated / stored. The above seems maybe as an "off topic" answer, or overkill, but I think it is a far better approach than spreading setTimeouts around the code.

Backbone collection fetch (add:true) does not update the collection

loadMore: function(){
var $this = this;
console.log(this.Messages); //SAME AS AFTER
this.Messages.url = '/js/messages/?start=' + this.Messages.length
this.Messages.fetch({'add':true,
success:function(){
console.log($this.Messages); //SAME AS BEFORE??
},
error:function(){
}
});
},
The collection is not updated. After this function, the events are fired, and the new items are drawn on the screen. The problem is that the collection did not add the new models.

As was mentioned in a previous answer the add option was removed in 1.0.0. You can accomplish the same thing by passing remove: false instead. From the docs:
The behavior of fetch can be customized by using the available set
options. For example, to fetch a collection, getting an "add" event
for every new model, and a "change" event for every changed existing
model, without removing anything: collection.fetch({remove: false})

Backbone.Collection.fetch():
fetch: function(options) {
options = options ? _.clone(options) : {};
if (options.parse === void 0) options.parse = true;
var success = options.success;
options.success = function(collection, resp, options) {
var method = options.update ? 'update' : 'reset';
collection[method](resp, options);
if (success) success(collection, resp, options);
};
return this.sync('read', this, options);
},
So what's up here is, your passed in function is assigned to var succees.
collection[method](resp, options); Is called and in your case method is 'reset'.
collection.reset has to go through and add all your models, fire all the events on the way. I don't know exactly what's going on but it goes through collection.reset, collection.add, model.add, etc...I didn't follow it all.
I'm not sure what the problem is exactly, I'm sorry about that. I hope I can at least help you try some things so maybe we can figure it out. The line if (success) success(collection, resp, options) is the call to your succes function. What you might try doing is having your success callback accept the passed back arguments and do some consoling of those out:
success: function(collection, resp, options) {
console.log(collection); // this might do the trick.
// if not, you could try the following
collection.on("reset", function(c, options) {
console.log(c); // see what that gives ya.
});
}
Another thing is, I couldn't find anywhere in the source or the docs where collection.fetch takes an add option. If I missed it, please let me know I'd like to look it over.
Good luck, let me know what you find. It might be worth trailing through with a step through debugger too.
Shit, it strikes me also that console has often showed me the most up to date version of collection objects when it shouldn't have.
try consoling out the lenghts of the collections instead or something:
var len = $this.Messages.length;
console.log(len);
//...
// or in the success callback
var len = collection.length;
console.log(len);

Backbone 1.0 removes this feature, breaking code that depends on this:
http://backbonejs.org/#Collection-fetch
Compare with:
"If you'd like to add the incoming models to the current collection, instead of replacing the collection's contents, pass {add: true} as an option to fetch."
http://htmlpreview.github.com/?https://raw.github.com/documentcloud/backbone/0.9.2/index.html#Collection-fetch
I suggest reverting to an older version of Backbone until this issue is fixed.

in backbone 1.0, you have to trigger reset by hand:
youColloection.fetch({reset: true});

Tracing knockout events

I have a jQuery grid plugin I am creating based on KnockoutJS 2.2.1. So far it is coming along well, but when the plugin is initialized on an element, the 'computed' loadGrid method invokes 3 times.
Just for a little context I am including the loadGrid method and some other related code. (The actual plugin is quite large so for brevity I only am including part of the plugin)
function GridDataModel() {
var self = this;
self.gridState = {
currentPage: ko.observable(opts.gridState.currentPage),
pageSize: ko.observable(opts.gridState.pageSize),
totalPages: ko.observable(opts.gridState.totalPages),
orderBy: ko.observable(opts.gridState.orderBy),
};
self.loadGrid = ko.computed({
read: function () {
console.log('load grid');
if (opts.dataUrl != '') {
var requestData = self.gridState;
if (self.columns.length == 0) requestData.needColumns = true;
$.getJSON(opts.dataUrl, requestData, function (data, textStatus, jqXHR) {
self.loadData(data);
});
}
},
owner: this,
deferEvaluation: false
});
}
gridDataModel = new GridDataModel();
ko.applyBindings(gridDataModel);
Notice the only dependency this computed has is on self.gridState which isn't changing to my knowledge.
I need to determine what is causing the initialization to call the load 3 times. I know loadGrid gets called when defined (b/c deferEvaluation == false), but I need to find out what is causing the other two events to fire.
So for the question...What is a way to trace what event causes a computed to reevaluate?
On another note, I set deferEvaluation : true but when I issue
gridDataModel.gridState.currentPage.valueHasMutated()
The computed does not fire. So the only way I can even get the computed to work is if deferEvaluation == false.

Chrome developer tools on the 'Sources' tab might be able to help. Just check out the panels on the right that will let you set breakpoints on various DOM elements.
See this overview of the scripts panel (now named the 'Sources' panel) or this overview of creating breakpoints on DOM events for more help.

I use the knockoutjs chrome plugin and I use messages for KO, that way you can display stuff to the console. Example of what I did in the past.
self.messages.push(response.msg);

CKEditor instance already exists

I am using jquery dialogs to present forms (fetched via AJAX). On some forms I am using a CKEditor for the textareas. The editor displays fine on the first load.
When the user cancels the dialog, I am removing the contents so that they are loaded fresh on a later request. The issue is, once the dialog is reloaded, the CKEditor claims the editor already exists.
uncaught exception: [CKEDITOR.editor] The instance "textarea_name" already exists.
The API includes a method for destroying existing editors, and I have seen people claiming this is a solution:
if (CKEDITOR.instances['textarea_name']) {
CKEDITOR.instances['textarea_name'].destroy();
}
CKEDITOR.replace('textarea_name');
This is not working for me, as I receive a new error instead:
TypeError: Result of expression 'i.contentWindow' [null] is not an object.
This error seems to occur on the "destroy()" rather than the "replace()". Has anyone experienced this and found a different solution?
Is is possible to 're-render' the existing editor, rather than destroying and replacing it?
UPDATED
Here is another question dealing with the same problem, but he has provided a downloadable test case.

For this to work you need to pass boolean parameter true when destroying instance:
var editor = CKEDITOR.instances[name];
if (editor) { editor.destroy(true); }
CKEDITOR.replace(name);

function loadEditor(id)
{
var instance = CKEDITOR.instances[id];
if(instance)
{
CKEDITOR.remove(instance);
}
CKEDITOR.replace(id);
}

I had this problem too, but I solved it in a much simpler way...
I was using the class "ckeditor" in my jQuery script as the selector for which textareas I wanted use for CKEditor. The default ckeditor JS script also uses this class to identify which textareas to use for CKEditor.
This meant there is a conflict between my jQuery script and the default ckeditor script.
I simply changed the class of the textarea and my jQuery script to 'do_ckeditor'(you could use anything except "ckeditor") and it worked.

This is the simplest (and only) solution that worked for me:
if(CKEDITOR.instances[editorName])
delete CKEDITOR.instances[editorName];
CKEDITOR.replace(editorName);
Deleting this entry in the array prevents this form safety check from destroying your application.
destroy() and remove() did not work for me.

Perhaps this will help you out - I've done something similar using jquery, except I'm loading up an unknown number of ckeditor objects. It took my a while to stumble onto this - it's not clear in the documentation.
function loadEditors() {
var $editors = $("textarea.ckeditor");
if ($editors.length) {
$editors.each(function() {
var editorID = $(this).attr("id");
var instance = CKEDITOR.instances[editorID];
if (instance) { instance.destroy(true); }
CKEDITOR.replace(editorID);
});
}
}
And here is what I run to get the content from the editors:
var $editors = $("textarea.ckeditor");
if ($editors.length) {
$editors.each(function() {
var instance = CKEDITOR.instances[$(this).attr("id")];
if (instance) { $(this).val(instance.getData()); }
});
}
UPDATE: I've changed my answer to use the correct method - which is .destroy(). .remove() is meant to be internal, and was improperly documented at one point.

var e= CKEDITOR.instances['sample'];
e.destroy();
e= null;

I've had similar issue where we were making several instances of CKeditor for the content loaded via ajax.
CKEDITOR.remove()
Kept the DOM in the memory and didn't remove all the bindings.
CKEDITOR.instance[instance_id].destroy()
Gave the error i.contentWindow error whenever I create new instance with new data from ajax. But this was only until I figured out that I was destroying the instance after clearing the DOM.
Use destroy() while the instance & it's DOM is present on the page, then it works perfectly fine.

For ajax requests,
for(k in CKEDITOR.instances){
var instance = CKEDITOR.instances[k];
instance.destroy()
}
CKEDITOR.replaceAll();
this snipped removes all instances from document.
Then creates new instances.

The i.contentWindow is null error seems to occur when calling destroy on an editor instance that was tied to a textarea no longer in the DOM.
CKEDITORY.destroy takes a parameter noUpdate.
The APIdoc states:
If the instance is replacing a DOM element, this parameter indicates whether or not to update the element with the instance contents.
So, to avoid the error, either call destroy before removing the textarea element from the DOM, or call destory(true) to avoid trying to update the non-existent DOM element.
if (CKEDITOR.instances['textarea_name']) {
CKEDITOR.instances['textarea_name'].destroy(true);
}
(using version 3.6.2 with jQuery adapter)

This is what worked for me:
for(name in CKEDITOR.instances)
{
CKEDITOR.instances[name].destroy()
}

CKEDITOR.instances = new Array();
I am using this before my calls to create an instance (ones per page load). Not sure how this affects memory handling and what not. This would only work if you wanted to replace all of the instances on a page.

I've prepared my own solution based on all above codes.
$("textarea.ckeditor")
.each(function () {
var editorId = $(this).attr("id");
try {
var instance = CKEDITOR.instances[editorId];
if (instance) { instance.destroy(true); }
}
catch(e) {}
finally {
CKEDITOR.replace(editorId);
}
});
It works perfectly for me.
Sometimes after AJAX request there is wrong DOM structure.
For instace:
<div id="result">
<div id="result>
//CONTENT
</div>
</div>
This will cause issue as well, and ckEditor will not work. So make sure that you have correct DOM structure.

i had the same problem with instances, i was looking everywhere and finally this implementation works for me:
//set my instance id on a variable
myinstance = CKEDITOR.instances['info'];
//check if my instance already exist
if (myinstance) {
CKEDITOR.remove(info)
}
//call ckeditor again
$('#info').ckeditor({
toolbar: 'Basic',
entities: false,
basicEntities: false
});

You can remove any ckeditor instance by remove method of ckeditor. Instance will be id or name of the textarea.
if (CKEDITOR.instances[instance_name]) {
CKEDITOR.remove(CKEDITOR.instances[instance_name]);
}

Indeed, removing the ".ckeditor" class from your code solves the issue. Most of us followed the jQuery integration example from the ckeditor's documentation:
$('.jquery_ckeditor')
.ckeditor( function() { /* callback code */ }, { skin : 'office2003' } );
and thought "... maybe I can just get rid or the '.jquery_' part".
I've been wasting my time tweaking the callback function (because the {skin:'office2003'} actually worked), while the problem was coming from elsewhere.
I think the documentation should mention that the use of "ckeditor" as a class name is not recommended, because it is a reserved keyword.
Cheers.

I learned that
delete CKEDITOR.instances[editorName];
by itself, actually removed the instance. ALL other methods i have read and seen, including what was found here at stackoverflow from its users, did not work for me.
In my situation, im using an ajax call to pull a copy of the content wrapped around the and 's. The problem happens to be because i am using a jQuery .live event to bind a "Edit this document" link and then applying the ckeditor instance after success of the ajax load. This means, that when i click another link a link with another .live event, i must use the delete CKEDITOR.instances[editorName] as part of my task of clearing the content window (holding the form), then re-fetching content held in the database or other resource.

I hade the same problem with a jQuery Dialog.
Why destroy the instance if you just want to remove previous data ?
function clearEditor(id)
{
var instance = CKEDITOR.instances[id];
if(instance)
{
instance.setData( '' );
}
}

I chose to rename all instances instead of destroy/replace - since sometimes the AJAX loaded instance doesn't really replace the one on the core of the page... keeps more in RAM, but less conflict this way.
if (CKEDITOR && CKEDITOR.instances) {
for (var oldName in CKEDITOR.instances) {
var newName = "ajax"+oldName;
CKEDITOR.instances[newName] = CKEDITOR.instances[oldName];
CKEDITOR.instances[newName].name = newName;
delete CKEDITOR.instances[oldName];
}
}

I am in the situation where I have to controls that spawn dialogs, each of them need to have a ckeditor embedded inside these dialogs. And it just so happens the text areas share the same id. (normally this is very bad practice, but I have 2 jqGrids, one of assigned items and another of unassigned items.) They share almost identical configuration. Thus, I am using common code to configure both.
So, when I load a dialog, for adding rows, or for editing them, from either jqGrid; I must remove all instances of CKEDITOR in all textareas.
$('textarea').each(function()
{
try
{
if(CKEDITOR.instances[$(this)[0].id] != null)
{
CKEDITOR.instances[$(this)[0].id].destroy();
}
}
catch(e)
{
}
});
This will loop over all textareas, and if there is a CKEDITOR instance, then destroy it.
Alternatively if you use pure jQuery:
$('textarea').each(function()
{
try
{
$(this).ckeditorGet().destroy();
}
catch(e)
{
}
});

remove class="ckeditor" , it might have triggered ckeditor initialization

I had the same problem where I was receiving a null reference exception and the word "null" would be displayed in the editor. I tried a handful of solutions, including upgrading the editor to 3.4.1 to no avail.
I ended up having to edit the source. At about line 416 to 426 in _source\plugins\wysiwygarea\plugin.js, there's a snippet like this:
iframe = CKEDITOR.dom.element.createFromHtml( '<iframe' + ... + '></iframe>' );
In FF at least, the iframe isn't completely instantiated by the time it's needed. I surrounded the rest of the function after that line with a setTimeout function:
iframe = CKEDITOR.dom.element.createFromHtml( '<iframe' + ... + '></iframe>' );
setTimeout(function()
{
// Running inside of Firefox chrome the load event doesn't bubble like in a normal page (#5689)
...
}, 1000);
};
// The script that launches the bootstrap logic on 'domReady', so the document
...
The text renders consistently now in the modal dialogs.

To support dynamic (Ajax) loading of forms (without page refreshes between) which contain textareas with the same (same form is called again) or different ID's (previously unloaded form) and convert them to CKEditor elements I did the following (using the JQuery adapter):
After the page has finished every Ajax call that delivers a textarea to be converted, I make a call to the following function:
setupCKeditor()
This looks like this (it assumes your textareas to be converted to RTE's have class="yourCKClass"):
/* Turns textAreas into TinyMCE Rich Text Editors where
* class: tinymce applied to textarea.
*/
function setupCKeditor(){
// define editor configuration
var config = {skin : 'kama'};
// Remove and recreate any existing CKEditor instances
var count = 0;
if (CKEDITOR.instances !== 'undefined') {
for(var i in CKEDITOR.instances) {
var oEditor = CKEDITOR.instances[i];
var editorName = oEditor.name;
// Get the editor data.
var data = $('#'+editorName).val();
// Check if current instance in loop is the same as the textarea on current page
if ($('textarea.yourCKClass').attr('id') == editorName) {
if(CKEDITOR.instances[editorName]) {
// delete and recreate the editor
delete CKEDITOR.instances[editorName];
$('#'+editorName).ckeditor(function() { },config);
count++;
}
}
}
}
// If no editor's exist in the DOM, create any that are needed.
if (count == 0){
$('textarea.yourCKClass').each( function(index) {
var editorName = $(this).attr('id');
$('#'+editorName).ckeditor(function() { $('#'+editorName).val(data); },config);
});
}
}
I should mention that the line:
$('#'+editorName).ckeditor(function() { $('#'+editorName).val(data); },config);
could (and should) be simply:
$('#'+editorName).ckeditor(function() { },config);
however I found that the editor would often show the correct content for a second after loading and them empty the editor of the desired content. So that line with the callback code forces the CKEditor content to be the same as the originating textarea content. Causes a flicker when used. If you can avoid using it, do so..

I had exactly the same problem like jackboberg. I was using dynamic form loading into jquery dialogs then attaching various widgets (datepickers, ckeditors etc...).
And I tried all solutions noted above, none of them worked for me.
For some reason ckeditor only attached the first time I loaded form, the second time I got exactly the same error message jackboberg did.
I've analyzed my code and discovered that if you attach ckeditor in "mid-air" that is while form content is still not placed into dialog, ckeditor won't properly attach its bindings. That is since ckeditor is attached in "mid-air", second time you attach it in "mid-air"... poof ... an error is thrown since the first instance was not properly removed from DOM.
This was my code that ptoduced the error:
var $content = $(r.content); // jQuery can create DOM nodes from html text gotten from <xhr response> - so called "mid-air" DOM creation
$('.rte-field',$content).ckeditor(function(){});
$content.dialog();
This is the fix that worked:
var $content = $(r.content).dialog(); // first create dialog
$('.rte-field',$content).ckeditor(function(){}); // then attach ckeditor widget

I ran into this exact same thing and the problem was that the wordcount plugin was taking too long to initialize. 30+ seconds. The user would click into the view displaying the ckeditor, then cancel, thereby ajax-loading a new page into the dom. The plugin was complaining because the iframe or whatever contentWindow is pointing to was no longer visible by the time it was ready to add itself to the contentWindow. You can verify this by clicking into your view and then waiting for the Word Count to appear in the bottom right of the editor. If you cancel now, you won't have a problem. If you don't wait for it, you'll get the i.contentWindow is null error. To fix it, just scrap the plugin:
if (CKEDITOR.instances['textarea_name'])
{
CKEDITOR.instances['textarea_name'].destroy();
}
CKEDITOR.replace('textarea_name', { removePlugins: "wordcount" } );
If you need a word counter, register for the paste and keyup events on the editor with a function that counts the words.

For those using the jquery "adapter" and having trouble (as I was), as super hackish yet working solution is to do something like this:
// content editor plugin
(function($){
$.fn.contentEditor = function( params ) {
var xParams = $.extend({}, $.fn.contentEditor.defaultParams, params);
return this.each( function() {
var $editor = $(this);
var $params = $.extend({}, xParams, $editor.data());
// if identifier is set, detect type based on identifier in $editor
if( $params.identifier.type ) {
$params.type = $editor.find($params.identifier.type).val();
}
$editor.data('type', $params.type);
// edit functionality
editButton = $('<button>Edit Content</button>').on('click',function(){
// content container
var $cc = $('#' + $editor.data('type'));
// editor window
var $ew = $('<form class="editorWindow" />');
$ew.appendTo('body');
// editor content
$ec = $('<textarea name="editorContent" />').val($cc.html());
$ec.appendTo($ew);
$ec.ckeditor();
//$ec.ckeditorGet().setMode('source');
$ew.dialog({
"autoOpen": true,
"modal": true,
"draggable": false,
"resizable": false,
"width": 850,
"height": 'auto',
"title": "Content Editor",
"buttons": {
'Save': function() {
$cc.html( $ec.val() );
$ec.ckeditorGet().destroy();
$ew.remove();
},
'Cancel / Close': function() {
$ec.ckeditorGet().destroy();
$ew.remove();
}
},
'close': function() {
$ec.ckeditorGet().destroy();
},
'open': function() {
$ew.find('a.cke_button_source').click();
setTimeout(function(){
$ew.find('a.cke_button_source.cke_on').click();
}, 500);
}
});
return false;
});
editButton.appendTo( $editor );
});
}
// set default option values
$.fn.contentEditor.defaultParams = {
'identifier': {
'type': 'input[name="type"]'
}
};
})(jQuery);
$(function(){
$('form.contentEditor').contentEditor();
});
The key point being this part:
'open': function() {
$ew.find('a.cke_button_source').click();
setTimeout(function(){
$ew.find('a.cke_button_source.cke_on').click();
}, 500);
}
This fixes the problem with the editor text not being visible the next time you open the dialog. I realise this is very hackish, but considering that most of these are going to be used for admin tools, I don't think that's as big a concern as it normally would be.. and this works, so hopefully it will save someone some time ;)

This is the fully working code for jquery .load() api and ckeditor, in my case I am loading a page with ckeditor into div with some jquery effects. I hope it will help you.
$(function() {
runEffect = function(fileload,lessonid,act) {
var selectedEffect = 'drop';
var options = {};
$( "#effect" ).effect( selectedEffect, options, 200, callback(fileload,lessonid,act) );
};
function callback(fileload,lessonid,act) {
setTimeout(function() {//load the page in effect div
$( "#effect" ).load(fileload,{lessonid:lessonid,act:act});
$("#effect").show( "drop",
{direction: "right"}, 200 );
$("#effect").ajaxComplete(function(event, XMLHttpRequest, ajaxOptions) {
loadCKeditor(); //call the function after loading page
});
}, 100 );
};
function loadCKeditor()
{//you need to destroy the instance if already exist
if (CKEDITOR.instances['introduction'])
{
CKEDITOR.instances['introduction'].destroy();
}
CKEDITOR.replace('introduction').getSelection().getSelectedText();
}
});
===================== button for call the function ================================
<input type="button" name="button" id="button" onclick="runEffect('lesson.php','','add')" >

Its pretty simple. In my case, I ran the below jquery method that will destroy ckeditor instances during a page load. This did the trick and resolved the issue -
JQuery method -
function resetCkEditorsOnLoad(){
for(var i in CKEDITOR.instances) {
editor = CKEDITOR.instances[i];
editor.destroy();
editor = null;
}
}
$(function() {
$(".form-button").button();
$(".button").button();
resetCkEditorsOnLoad(); // CALLING THE METHOD DURING THE PAGE LOAD
.... blah.. blah.. blah.... // REST OF YOUR BUSINESS LOGIC GOES HERE
});
That's it. I hope it helps you.
Cheers,
Sirish.

This functions works for me in CKEditor version 4.4.5, it does not have any memory leaks
function CKEditor_Render(CkEditor_id) {
var instance = CKEDITOR.instances[CkEditor_id];
if (CKEDITOR.instances.instance) {
CKEDITOR.instances.instance.destroy();
}
CKEDITOR.replace(CkEditor_id);
}
// call this function as below
var id = 'ckeditor'; // Id of your textarea
CKEditor_Render(id);

CKeditor 4.2.1
There is a lot of answers here but for me I needed something more (bit dirty too so if anyone can improve please do). For me MODALs where my issue.
I was rendering the CKEditor in a modal, using Foundation. Ideally I would have destoryed the editor upon closing, however I didn't want to mess with Foundation.
I called delete, I tried remove and another method but this was what I finally settled with.
I was using textarea's to populate not DIVs.
My Solution
//hard code the DIV removal (due to duplication of CKeditors on page however they didn't work)
$("#cke_myckeditorname").remove();
if (CKEDITOR.instances['myckeditorname']) {
delete CKEDITOR.instances['myckeditorname'];
CKEDITOR.replace('myckeditorname', GetCKEditorSettings());
} else {
CKEDITOR.replace('myckeditorname', GetCKEditorSettings());
}
this was my method to return my specific formatting, which you might not want.
function GetCKEditorSettings()
{
return {
linkShowAdvancedTab: false,
linkShowTargetTab: false,
removePlugins: 'elementspath,magicline',
extraAllowedContent: 'hr blockquote div',
fontSize_sizes: 'small/8px;normal/12px;large/16px;larger/24px;huge/36px;',
toolbar: [
['FontSize'],
['Bold', 'Italic', 'Underline', '-', 'NumberedList', 'BulletedList', '-', 'Link', 'Unlink'],
['Smiley']
]
};
}

Try this:
for (name in CKEDITOR.instances)
{
CKEDITOR.instances[name].destroy(true);
}