Javascript Remoting for APEX controller

Javascript remoting is the process that provides support for some methods in APEX controllers to be called via Javascript.The @RemoteAction annotation is currently available as a Developer preview.You have to contact Salesforce.com support to enable this feature.To use Javascript remoting, your request must take the following form:

[<namespace>.]<controller>.<method>([params...,] <callbackFunction>(result, event)
{
// callback function logic
}, {escape:true});

• namespace is your organization's namespace. This is only required if the class comes from an installed packaged.

• controller is the name of your Apex controller

• method is the name of the Apex method you're calling

• params is the comma–separated list of parameters that your method takes

• callbackFunction is the name of the function that handles the response from the controller. It returns the status of the call and the method result.

• escape defines whether your response should be escaped (by default, true) or not (false)

In controller, your Apex method declaration is preceded with the @RemoteAction annotation like this:

@RemoteAction
global static String getItemId(String objectName) { ... }

Example code:

/*VF page*/

<script type="text/javascript">
function updateStatus(input,id) {
var inputStatus=id;
shortList.doShortListThroughCheck(inputStatus,function(result,event){
if(input.checked){
 document.getElementById(id).value="Short Listed";
alert(document.getElementById(id).value);
}else{
 document.getElementById(id).value="New";
 alert(document.getElementById(id).value);
}
},{escape:true});
}</script>

/*@VF Component*/

<apex:selectCheckboxes onclick="updateStatus(this,'{!app.Name}');">
       </apex:selectCheckboxes>

/*In Controller*/

@RemoteAction
global static Applicant__c doShortListThroughCheck(String para){
    Applicant__c applicant;    
    try{
   applicant=[select Name, Name__c, Status__c from Applicant__c where Name =:para limit 1];
                 applicant.Status__c='Short Listed';     
           update applicant;   
                
    }catch(DMLException e){
         ApexPages.addMessages(e);
         return null;   
    }        
return null;
}