I need help to manipulate strings, but for example when I am programming an event with jquery and extract data from a textfield for example I can,t do this var msg=msg.subtring(0,5);

 

or for example this does not work->

 

//-------------------------
$("#btn_send").click(function(){
  var ide=$('#txt_ide').attr('value');
  var name=$('#txt_name').attr('value');
        var age=$('#txt_age').attr('value');
       
      if(age==null)

        alert("Type age");    
    
 });