Using backing bean value in javascript

Question

   
                              
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Answer 1

That's just because alert(#{test.i}); is evaluated when the commandButton is rendered. You can see the changed value by telling JSF to render the script again:

<h:commandButton value="click me" action="#{testClass.testfxn()}">
    <f:ajax render="out" />
</h:commandButton>
<h:panelGroup id="out">
    <h:outputScript>
         alert(#{testClass.i});
    </h:outputScript>
</h:panelGroup>

Answer 2

Unlike Richfaces where you can directly call javascript function, primefaces you need to have javascript function as:

function_name(xhr, status, args)

Using listed CommandButton as Example:

 <p:commandButton value="GO" oncomplete="alert(#{test.i})"  actionListener="#{test.testfxn()}" update="@this"/>

In function test.testfxn() we have:

public void testfxn(){    
RequestContext reqCtx = RequestContext.getCurrentInstance();
        i = i++;
        reqCtx.addCallbackParam("i", i);
}

Here,In function call to backing bean from actionlistener the variables are added to RequestContext.

Now In javascript function:

function draw(xhr, status, args) {
    console.log("We are into draw function");
    jsonString = JSON.parse(args.i); //json variable is taken out from args variable.
    console.log("The value of i "+ i);
}