RAP/Incubator/ClientScripting

Overview

Conventional RAP applications are running almost entirely on a Server, with a thin client only rendering a user interface with some limited interactivity. This has several advantages, but it also means all application-relevant events have to be forwarded to the Server before being processed, causing small delays and traffic. Scenarios where interactions occur with a high frequency, like typing or mouse movements, would therefore be undesirable.

This is where RAP ClientScripting can help. ClientScripting allows developer to handle some of the events directly on the client, without creating any http-requests. This is ideal to customize or enhance the behavior of specific widgets, making it much less often necessary to develop RAP custom-widgets.

The scripts themselves are written in JavaScript on a SWT-like API. This allows application developer SWT-experience to get started right away, and makes porting between SWT/Java and RAP-ClientScripting fairly easy. Even without any JavaScript-experience, this document should provide you with all the basics.

The ClientScripting feature is currently in early development, aiming to enable only some specific usecases at first. However, all API published here should be stable and is unlikely (but currently not guarenteed) to change in the future. The project is currently hosted on GitHub.

JavaScript API

The Event Object

This object is given as the first argument when calling a client event listener function. Its API is designed after org.eclipse.swt.widgets.Event.

Field Summary
number	type the type of event, as defined by the event type constants in object SWT
Widget	widget an object representing the widget that issued the event.
boolean	doit depending on the event, a flag indicating whether the operation should be allowed. Setting this field to false will cancel the operation. Currently supported only for key and mouse events on Text and Text-like widgets.
string	doit depending on the event, the character represented by the key that was typed. This is the final character that results after all modifiers have been applied. For non-printable keys (like arrow-keys) this field is not set. Changing its value has no effect.
number	keycode depending on the event, the key code of the key that was typed, as defined by the key code constants in object SWT. When the character field of the event is ambiguous, this field contains the unaffected value of the original character. For example, typing Shift+M or M result in different characters ( 'M' and 'm' ), but the same keyCode (109, character code for 'm').
number	stateMask depending on the event, the state of the keyboard modifier keys and mouse masks at the time the event was generated.
number	button the button that was pressed or released; 1 for the first button, 2 for the second button, and 3 for the third button, etc.
number	x x coordinate of the pointer at the time of the event
number	y y coordinate of the pointer at the time of the event