Blackberry BROWSER VERSION 4.7.0 - FUNDAMENTALS GUIDE Основы - Страница 26

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Fundamentals Guide
BlackBerry Device
Software version
For more information about the BlackBerry Browser's JavaScript implementation, see the BlackBerry Browser JavaScript
Reference.

Support for AJAX and the XMLHttpRequest object

The BlackBerry® Browser introduced support for the XMLHttpRequest object in BlackBerry® Device Software version 4.6. You
can use the XMLHttpRequest object to transfer data between the BlackBerry Browser and the web server without reloading the
entire web page. You can use this object to send and retrieve XML, HTML, plain text, or other data types in the background.
Because access to the DOM is also available, you can update the web page when new data or content is retrieved to create
extremely responsive and dynamic web pages.
The BlackBerry Browser supports synchronous requests (the JavaScript® engine is blocked until it receives a response from the
server) and asynchronous requests (the JavaScript engine can process other JavaScript functions while it awaits a response).
However, because of the slower data transfer rates in a wireless browsing environment, requests made by this object should
almost always be asynchronous.
The XMLHttpRequest object can help to reduce the perceived latency that marks wireless browsing. Because requests are made
in the background, the user can continue to work with the current web page while new data is retrieved. Because smaller amounts
of data are parsed, the BlackBerry Browser can render modifications to the web page quickly.

Content navigation

Page navigation

Users can navigate through web pages in the BlackBerry® Browser differently depending on the BlackBerry device's input
methods. The BlackBerry Browser also includes shortcut keys for navigation operations.
Input method
trackwheel
24
Description
•
DOM Level 2 Events
The BlackBerry Browser also provides partial support for DOM Level 3 Events, including the
KeyboardEvent and TypeEvent objects.
Description
The trackwheel is primarily designed to scroll vertically. To scroll horizontally, the BlackBerry
device user must press the Alt key while they roll the trackwheel.
Content navigation