I would like to know what actually happens on re-render (Ajax Call and DOM replacement) in Salesforce.

My Idea:

  1. The ajax call is made to get data.
  2. On completion of the ajax call, the DOM is constructed(the new part).
  3. The DOM Element is updated/replaced.

Is the DOM updated or replaced?

My Scenario :

I have a Visualforce Page which has multiple input items. I binds keypress event to the input elements on document ready. An action function is present which re-renders a section of the page.

Now, the input elements in the re-rendered panel do not have a keypress event binding.

However, when I have the document.ready() script in the re-rendered output panel, the keypress event gets binded.

Can someone explain how exactly re-render works?


When a re-render occurs, only the portion of the DOM that is set to rerender is actually re-rendered. Therefore, any jQuery event bindings that you created on $(document).ready() are essentially lost for the portion of the DOM that was re-rendered. If you wrap these event binding calls in a function, it's easy to re-bind.

What I do in these scenarios is use the onComplete attribute of something like a commandLink to call a function to "re-bind" my event handlers. Here is an example...

<apex:commandLink action="{!doSomething}" rerender="Something" onComplete="bindEvents();">

And then my bindEvents function and also my $(document).ready()...

function bindEvents() {
  $('#myElement').click(function() {
    // implemtation

$(document).ready(function() {
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  • I understand the that DOM elements are not binded after re-rendering. But I'm trying to understand what actually happens on rerender. Thanks anyway! – Vignesh Damodharan Dec 20 '12 at 4:47
  • @Vignesh I explained exactly what happens on a re-render in the first paragraph of my response. Is there something else you are looking for? – Kevin O'Hara Dec 20 '12 at 11:21
  • Yeah! I get it. I was hoping if someone would explain me what re-render means(the DOM changes and stuff). – Vignesh Damodharan Dec 20 '12 at 13:12
  • I want to help but I am still confused on what you are looking for. Re-render means partial DOM re-rendering. It simply re-renders only the elements that are specified to re-render...not the whole DOM. This happens after the AJAX callback is received. Is the whole jQuery.ready() thing throwing you off? The reason that works when inside the re-rendered element is because the DOM is already loaded so the callback happens immediately. See here: jsfiddle.net/D3cQ4 – Kevin O'Hara Dec 20 '12 at 16:26
  • Thanks! I totally understand about the jQuery.ready() part. I'm trying to get exact details of what re-render means and how the ajax requests are done with the auto-generated ids. That's it! Thanks anyway! :) – Vignesh Damodharan Dec 21 '12 at 4:46

For this issue i use jQuery live function and don't care about DOM "updates":

<apex:inputText value="{!myVar}" id="myINput"/>

jQuery('[id$=myInput]').live('keypress', function(){
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  • I understand .live() will fix the issue. I'm trying to understand what actually happens on re-render. Is there any documentation on what exactly happens? Btw, thanks for the help! – Vignesh Damodharan Dec 19 '12 at 13:40
  • 4
    Just an FYI, jQuery.live() is deprecated. api.jquery.com/live – Kevin O'Hara Dec 19 '12 at 15:11
  • jQuery.live() is replaced by jQuery.on() . @KevinO'Hara 's approach is better though. – zuke Jan 11 '15 at 12:31
  • I prefer the approach from @KevinO'Hara but it seems you can still use .on() as a replacement for .live() if you're using delegated event handlers: api.jquery.com/on/#direct-and-delegated-events – Semmel Feb 28 '19 at 16:10

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