You can create JavaScript objects that contain the state and implement the behavior of a control. The controls take care of drawing themselves, including changing their appearance as a result of various state changes.
Create JavaScript to add screen controls. The following example adds a text box and a button.
var helloButton;
var nameField;
...
// Add a text box to the view
nameField = new TextField(null, "Enter your name");
mainView.addControl(nameField);
// Add a button to the view
helloButton = new FormButton(null, "Say Hello!");
helloButton.addEventListener("ActionPerformed", helloButtonClicked);
mainView.addControl(helloButton);
Figure: Hello World widget