title: set constraints on dijit.form.ValidationTextBox
body: <p>i am calling a function onblur .. that function call an ajax and that ajax get string .. </p>
  
  <p>now i want if value in string is avail .. then text box  become red ..</p>
  
  <p>my ajax code is</p>
  
  <pre><code>function ucheck(){
                  dojo.xhrPost({
                      // The URL to request
                      url: "ucheck",
                      timeout :  3000 ,
                      content: {
                      username: dojo.byId("pref_id").value
  
                      },
                      // The method that handles the request's successful result
                      // Handle the response any way you'd like!
                      load: function(result) {
                          var fi=result;
                          document.getElementById('co').innerHTML=fi // this is print the value in lable
  
  
                      }
                  });
              }
  </code></pre>