JSP onclick event before passing the variable it updates in link

I have a link in a jsp that looks like this:

<a href="link?var1=foo&var2=bar"target="_blank">text</a>

I have a开发者_高级运维 form submit submitFormAsync('Form'); that sets a variable ${design.textVar}

How can I set an onclick for this link to submit the form and then pass me the updated variable call it var3?

If you want to update your link's href then it must have an id in order for JavaScrpt to find it:

<a id="lnk" href="link?var1=foo&var2=bar" onclick="update();" target="_blank">text</a>

And then append your value to the href:

function update()
{
  var link = document.getElementById("lnk");
  link.href += "&var3=" + ${design.textVar};
  return;
}

UPDATE:

If your var3 value is retrieved asyncronously, then you don't need to use JSP variables, but use pure JavaScript:

function update()
{
  var link = document.getElementById("lnk");
  var result = submitFormAsync('Form');
  link.href += "&var3=" + result;
  return;
}

 function update()
   {
        var link = document.getElementById("lnk");
        var var3 = submitFormAsync('Form');

       var url =  link.href + "&var3=" +var3; 
       document.Form.action = url;
       document.Form.submit();  

  }