1. <h:selectOneMenu id="languageField"  >

  2.    <f:selectItem itemLabel="English" itemValue="eng" />

  3.    <f:selectItem itemLabel="Spanish" itemValue="spa" />

  4. </h:selectOneMenu>

  5. 

  6. <a4j:commandButton action="#{myBean.myFunction( 'param1', rich:findComponent('languageField').value )}"/ >