Disclaimer : This is an homework exercise. Sort of. I'm trying to learn Visualforce + APEX + web design in a very short term, so I'm asking my friends to put up challenging questions for me.

VF page


My aim : show an alert/message when the user presses a button. Using ActionFunction. I must use Action Function

Problems I am facing :

  1. Please look at my code VF page. I have marked the problem with a comment.
  2. I donot know enough about AJAX/JS to fulfill all requirements.
  3. The code is behaving weird.
  4. I can display the alert/message without Action Function, I dont know how WITH AF.
  5. The page refreshes after I click the button. Does a command button ALWAYS refresh after you click it?

I will expand on problem 1 :

If I remove the offending line, the code does not work. I click the button and page refreshes. NOTHING happens.

If I keep the offending line, when I click the button, it displays a JS alert and a few seconds later, it displays the Salesforce type error/message. WHY??

Is it possible to call a JS function from the controller?

My logic is like this :

  1. Click the button.
  2. It calls a JS function
  3. the JS function calls the function related to the Action Function, and THAT in turn calls the controller function associated with the AF.
  4. the controller calls back/returns value/changes a getter/setter to some value.
  5. the value is taken by some other JS function defined in the page and it triggers a condition check (I'm pulling words out of my @$$ here) and THAT displays and alert.
  6. phew

I hope this is not asking for the impossible??

I donot ask you folks to provide me a full detailed answer, just a few nudges in the right direction would be enough!! I dont need much hand holding.

Sorry for the wall of text.

1 Answer 1


Below is my VF page:

<apex:page controller="exampleCon">
function mtdOne(){  

alert('m inside javascript');



    <apex:form id="frm">

    <apex:outputText value="Clicked" id="showstate" rendered="{!flag}"/>

   <apex:commandButton value="Hit Me" onclick="mtdOne();return false;" />

    <apex:actionFunction action="{!sayhello}" name="controllermtd" rerender="frm">


Below is the controller:

/*** Controller ***/
public class exampleCon {

    public boolean flag{get;set;}
    public static integer i=1;

    public examplecon(){


    public PageReference sayHello() {


        return null;


Hope this helps you(I am rerendering outputtext using actionfunction in my example)

  • If this helps you, mark this as the solution
    – Abhijeet
    Jul 29, 2016 at 12:21
  • This IS the answer! Im sorry Im late, I couldnt get to a PC on the weekend. You're a wizard... but can you please explain whats happening in the commandbutton onlick part? Thanks!
    – fraglord
    Aug 1, 2016 at 7:01
  • in the onClick(), we basically call up the javascript method.Inside that javascript method, i am calling the controller method by referring its name.We can also pass parameters using <apex:param> Please refer to salesforce documentation for more understanding :)
    – Abhijeet
    Aug 1, 2016 at 11:26

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