4.1 Web Scripting
A web browser provides an ECMAScript host environment for
client-side computation including, for instance, objects that
represent windows, menus, pop-ups, dialog boxes, text areas,
anchors, frames, history, cookies, and input/ output. Further, the
host environment provides a means to attach scripting code to
events such as change of focus, page and image loading, unloading,
error and abort, selection, form submission, and mouse actions.
Scripting code appears within the HTML and the displayed page is a
combination of user interface elements and fixed and computed text
and images. The scripting code is reactive to user interaction and
there is no need for a main program.
A web server provides a different host environment for
server-side computation including objects representing requests,
clients, and files; and mechanisms to lock and share data. By using
browser-side and server-side scripting together, it is possible to
distribute computation between the client and server while
providing a customised user interface for a Web-based
application.
Each Web browser and server that supports ECMAScript supplies
its own host environment, completing the ECMAScript execution
environment.
