357 Lotus blogs updated hourly. Who will post next? Home | Downloads | Events | Pods | Blogs | Search | myPL | About 
 
Latest 7 Posts
MWLUG 2014 Slide Deck – Write once, run anywhere: Angular.js in XPages.
Tue, Sep 2nd 2014 141
Going to MWLUG 2014? You need to buy these guys a beer as well….
Sun, Aug 24th 2014 202
Going to MWLUG 2014? Buy Dave Leedy a beer
Sun, Aug 24th 2014 360
Chart Directives and Dynamic Binding – MWLUG 2014 preview
Wed, Aug 20th 2014 218
Accessing the original element when using Select2-focus
Sun, Aug 17th 2014 162
Angular in XPages #8 – Directives (did someone say plugins?)
Sun, Aug 10th 2014 195
Working on my MWLUG2014 presentation
Wed, Aug 6th 2014 223
Top 10
Arguably the most dangerous thing you could ever do in XPages – let other people use your eval() in their SSJS
Tue, Jun 18th 2013 1329
Why learning JavaScript is more critical to XPage developers than Java
Wed, Mar 26th 2014 1027
An open letter to Mr. NotesIn9
Wed, Apr 2nd 2014 682
Adding custom HTTP headers to Domino R9 using IBM HTTP Server (IHS)
Sun, Apr 20th 2014 658
Angular.js in XPages #1 – Using the right IDE for development
Sun, Apr 27th 2014 585
WebSockets comes to XPages!! Awesome – Awesome – Awesome
Tue, May 20th 2014 585
And the gloves are off……
Mon, Mar 31st 2014 564
EXTJS in XPages #14 – Grid editing and saving data via REST CRUD
Thu, Aug 1st 2013 549
EXTJS in XPages #13: Totaling your columns with a groupingSummary
Sun, Jun 30th 2013 547
Angular.js in XPages #6 – A People Manager CRUD application
Sun, Jun 1st 2014 514


XPages CSJS timing issue – what is ‘this’ ?
MarkyRoden    

Problem

The JavaScript object represented by ‘this’ does not appear to be as expected.

The problem is caused because of the way that XPages adds events to DOM objects through the <xp:eventHandler>

The Situation

I wanted to pass the id from a button to a function. Outside of XPages I would normally acheive this by passing a reference to the button(this) to a function (saySomething in this case) and then extracting the id from the object passed:

function saySomething(obj){
	alert("This is my object - "+this
		+"nnThis is my id - "+
		this.id)
}

Describing 'this' when passed from a button to a function

Describing 'this' when passed from a button to a function

	<button id="markyButton" onclick="saySomething(this)"></button>

In this case I am passing the “this” object to the function.

this

is an object reference to the DOM element which it was generated from – for some serious stuff on ‘this’ check out this article

http://www.quirksmode.org/js/this.html

XPages fail :(

However when I add the JavaScript to the XPages button and add the code through the GUI Designer interface

Adding JavaScript through the XPages GUI

Adding JavaScript through the XPages GUI

I do not get the expected result when I click on the button……

Not what we expected

Not what we expected

The Explanation…

The reason this happens is because of the way that XPages assigns events to objects in the webpage. If you have ever looked at the source of an XPages you will almost certainly have seen a whole load code like this at the end of the page

XSP.addOnLoad(function() {
XSP.attachEvent(".....
}

and this is how the XPage adds the event to the object – in the case of this example the XPages creates our button in the HTML but as you can see there is no onclick event initially assigned to it

		<button class="lotusBtn" type="button" name="view:_id1:_id2:_id37:button1" id="view:_id1:_id2:_id37:button1">Click This</button>

and then at the bottom of the web page source code we can see the assignment of the event after during the “addOnLoad” which means after the page has loaded.

<script type="text/javascript">

function view__id1__id2__id37__id40_clientSide_onclick(thisEvent) {
alert("This is my object - "+this+"nnThis is my id - "+this.id)

}

XSP.addOnLoad(function() {
XSP.attachEvent("view:_id1:_id2:_id37:_id40", "view:_id1:_id2:_id37:button1", "onclick", view__id1__id2__id37__id40_clientSide_onclick, false, 2);
});

</script>

What is happening?

The XPage is adding the function “view__id1__id2__id37__id40_clientSide_onclick” to the “onclick” event of the “view:_id1:_id2:_id37:button1″ DOM element (our button in this case).

The nuances of this are subtle but important – the code is not adding “alert(whetever)” to the onclick event it is adding a function call to the onclick event.

So. when the button is clicked the function view__id1__id2__id37__id40_clientSide_onclick executes it’s code and in that situation ‘this’ no longer refers to the button.

The difference is clear when we look at the resulting code side by side

<button value="or Click this" id="button3" onclick='alert("This is my object - "+this+"nnThis is my id - "+this.id)'></button>

or

<button value="or Click this" id="button3" onclick='view__id1__id2__id37__id40_clientSide_onclick()'></button>

“this” is never passed to the view__id1__id2__id37__id40_clientSide_onclick() function and therefore any reference to the button is lost.

When the function executes – “this” refers to the function (which isn’t an object) and therefore we get the window (the webpage) as a failover.

The solution

If you need to do something like this then add the onclick event to the source pane.

Here is the XML markup for the XPages generated event (which fails me)

		<xp:button value="Click This" id="button1">
			<xp:eventHandler event="onclick" submit="false">
				<xp:this.script>
					<![CDATA[alert("This is my object - "+this+"nnThis is my id - "+this.id)]]>
				</xp:this.script>
			</xp:eventHandler>
		</xp:button>

and the XML markup  for the manually added onclick event (which works)

		<xp:button value="or Click this" id="button2"
			onclick='alert("This is my object - "+this+"nnThis is my id - "+this.id)'>
		</xp:button>

The demonstration

Here is a simple demo of the problem and the solution




---------------------
http://xomino.com/2012/04/09/xpages-csjs-timing-issue-what-is-this/
Apr 08, 2012
88 hits



Recent Blog Posts
141


MWLUG 2014 Slide Deck – Write once, run anywhere: Angular.js in XPages.
Tue, Sep 2nd 2014 1:05p   Mark Roden
Here is the slide deck for those interested – thank you to everyone who attended the presentation and I look forward to talking more on the subject in the future. http://www.slideshare.net/MarkRoden/angularjs-in-xpages [read] Keywords: xpages
202


Going to MWLUG 2014? You need to buy these guys a beer as well….
Sun, Aug 24th 2014 8:07p   Mark Roden
—->>>> Richard Moy [read] Keywords:
360


Going to MWLUG 2014? Buy Dave Leedy a beer
Sun, Aug 24th 2014 5:37p   Mark Roden
Yeah I know I have rattled on about this before but it holds as true today as it does any other day before. Here is a list of reasons you should buy Dave Leedy a beer in case you were wondering… 1) really? You need a list?? Shame on you…. 2) NotesIn9 has helped you – One of those videos by Dave, John, John, Brian, Chris, Graham, Jeremy, Mark, Mark, Paul, Peter, Steve, Tim, Chris, Paul, Josh, Dan, Niklas, Michael, Russ, Serdar, Sean, Mark, Brad, Frederick, Steve, Richard, Kathy, [read] Keywords: ibm community
218


Chart Directives and Dynamic Binding – MWLUG 2014 preview
Wed, Aug 20th 2014 7:13p   Mark Roden
Although not directly related to the purpose of the presentation I am going to demonstrate how to use an Angular.js chart directive to bind to the application service data and create dynamic charting within the application. Changing the Zip for 1 Marky not only updates the data displayed – but also because of the data bind – auto-magically updates the chart While this in itself does not directly relate to the write once and run anywhere nature of the presentation – it d [read] Keywords: application
162


Accessing the original element when using Select2-focus
Sun, Aug 17th 2014 7:36p   Mark Roden
In the application we are currently working on I wanted to add an ajax call to a JSON service, but only for certain fields. Rather than go through the application and add the code to every element I used a delegated focus event for the field with an attribute of  “help_fieldName”. The following HTML represents the code on the form: UK US Global First Name Last Name The following jQuery code makes it work. The getHelp function shows/hides [read] Keywords: ajax application xml
195


Angular in XPages #8 – Directives (did someone say plugins?)
Sun, Aug 10th 2014 8:08p   Mark Roden
In this article I will discuss Angular Directives and why they are near and dear to my heart Directives Directives in Angular are modular pieces of functionality which in some cases are very analogous to plugins in jQuery. According to the Angular documentation… “At a high level, directives are markers on a DOM element (such as an attribute, element name, comment or CSS class) that tell AngularJS’s HTML compiler ($compile) to attach a specified behavior to that DOM element or [read] Keywords: xpages application css
223


Working on my MWLUG2014 presentation
Wed, Aug 6th 2014 8:04p   Mark Roden
Just wanted to show a work in progress – screenshots of what I am working on for MWLUG2014. Part of the presentation is showing how to make your Angular applications portable. My sample app will be the one I created as part of the Angular in XPages series. I will walk through the code and demonstrate how I can take this stand alone application and insert it into this bootstrap demo dashboard application creating this fully functional component capability within the dashboard With [read] Keywords: xpages application applications




349


Angular.js in XPages #7 – Writing better code using Services
Sun, Aug 3rd 2014 6:01p   Mark Roden
In this article I will discuss a better programming practice for Angular.js than was demonstrated in the previous articles within this series. I have mentioned before, part of the purpose this blog is very much a “learning in progress” for me. Without going through the previous articles I would not have been able to get to this point and write “better code”. Hopefully with that understanding, those of you who have been along for the ride will appreciate this and grow w [read] Keywords: agent lotusscript xpages application twitter
319


Taking back productivity in Domino Designer (a NotesIn9 production)
Tue, Jul 29th 2014 3:27p   Mark Roden
Yeah it has been a while (over 18 months) since the last time I did a NotesIn9 video but it finally happened again. NotesIn9 149:  Database Resources and Design Definition Doesn’t sound very exciting does it? Dave needs to work on his attention grabbing heading show names. I would have called it something more like this – but then who am I to complain – it is not my show after all ;) NotesIn9 149:  Taking back productivity in Domino Designer  This video revolves around som [read] Keywords: domino notes xpages database eclipse
271


The consummate Champion
Thu, Jul 24th 2014 8:42p   Mark Roden
As Russ Maher said today in Hey Who got the Handsome Champion it is an honor and a privilege to not only be recognized by IBM as a Champion for ICS 2014, but you also get some very cool stuff. Thanks to Amanda Bauman and Oliver Heinz for organizing “the champions” and all the gear. I just wonder what I am going to do with all of it :) Seriously though, I am very humbled to be an IBM Champion ! Thank you to everyone who nominated me and made this possible :) [read] Keywords: ibm




Created and Maintained by Yancy Lent - About - Blog Submission - Suggestions - Change Log - Blog Widget - Advertising - Mobile Edition