<script language="javascript">

      function displayMsg() {
          setwindowOverlayPos('popup_window',  - 100,  - 150);
      }

      window.onload = function () {

     // this is the enum value I want to check. if the value is cust1 ,  I call the popup window.

          var cust1= '#{myBean.customerType.custType == "cust1"}';

          if(cust1){
            displayMsg();
          }

      }
 </script>

public enum CustomerTypeEnum {


CUST1("CUST1"),
CUST2("CUST2");

private String custType;

private CustomerTypeEnum(String s) {
    custType = s;
}

/**
 * @return customer type
 */
public String CustomerTypeEnum() {
    return custType;
}

@ManagedBean(name = "home")
@ViewScoped
public class HomeBean extends BaseOrderStepBean {

     private CustomerTypeEnum customerType;

     public void method1(){

         customerType = CustomerTypeEnum.CUST1;
     }


}