just now i opened immediate window,it was given some warning like Warning: Cannot debug script code. Script debugging is disabled for the application you are debugging. Please uncheck the 'Disable script debugging' option on the Internet Options dialog box (Advanced page) for Internet Explorer and restart the process.so that i opened internet options and unchecked it. now my page including the js file and getting error like 'Object required',it is showing error on onclick event.

if i am irritating to you then sorry for it,

i tried like this after getting error,its working fine
button1.Attributes.Add("onclick","return test1(' " & txt1.ClientId& " ')")

function test1(s)
     {
       var t=document.getElementById(s);
           if (t.value=="")
               {
                 alert("testing");
                 return false;
               }
      return true;
  }
 }

,but how can i pass here 18 controls ids,it is not possible right,so that i dont want to pass any parameter to my function,without passing parameter is it possible to fire this function

i got it.
//code behind
button1.Attributes.Add("onclick","return test1()")

// above function is belongs to .js file

function test1()
     {
       var t=document.getElementById("txt1"); //here txt1 is textbox control name.
           if (t.value=="")
               {
                 alert("testing");
                 return false;
               }
      return true;
  }
 }

Glad you got it working.

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