Hi Radha,

Please check below link

http://sfdcsrini.blogspot.com/2014/07/visualforce-action-function-example.html

Controller Class:


public class ActionFunctionCLS {
  public Account actObj{get;set;}
   PageReference prf= null;
    public ActionFunctionCLS(){
      actObj = new Account();
    }
 
   
    public pagereference Saverec(){
   if(actobj.Name !=''){
    insert actobj;
   
   }
   else{
     ApexPages.Message myMsg = new ApexPages.Message(ApexPages.Severity.ERROR,'Error: Please Enter Name.');
     ApexPages.addMessage(myMsg);
   
   }
   if(actobj.id !=null){
  
      // Send the user to the detail page for the new account.
      prf = new PageReference('/'+actobj.id);
      prf.setRedirect(true);
   
   }
   return prf;
    }

}


Visualforce Page:

<apex:page controller="ActionFunctionCLS" id="pg" >
  <script>
   function recSave(){
    var accountType = document.getElementById('pg:fm:pb:pbs:actType').value;
    alert('accountType -->'+accountType);
    if(accountType != 'Prospect'){
     alert('You Should Select Prospect to Save the Record');
     return false;
    }
    else{
     saveAccount(); //this is the function name which calls our action function from java Script.
     return true;
    }
   }
 
  </script> 

 <apex:form id="fm">
  <apex:actionfunction name="saveAccount" action="{!Saverec}" />
   <apex:pageBlock id="pb">
     <apex:pagemessages ></apex:pagemessages>
     <apex:pageblockButtons >
      <apex:commandButton value="Save" onclick="recSave();return false;"/>    
     </apex:pageblockButtons>
    
     <apex:pageblockSection id="pbs">
       <apex:inputField value="{!actobj.Name}" id="actName"/>
       <apex:inputField value="{!actobj.type}" id="actType"/>
     </apex:pageblockSection>
   </apex:pageBlock>
 </apex:form>
</apex:page>

In command button onclick event need to give javascript function and from javascript fuction we need to call action function name, While calling time we need pass array to param tag.

If this help for you make it Best Ans

Thanks 
Jayabalaji