tailieunhanh - build your own ajax web applications PHẦN 2

phần của chức năng. Loại tính năng này được sử dụng chỉ tồn tại trong các ứng dụng máy tính để bàn, nhưng bây giờ nó hoạt động giống như trong trình duyệt, nhờ vào DOM. phần của chức năng. Loại tính năng này được sử dụng chỉ tồn tại trong các ứng dụng máy tính để bàn, nhưng bây giờ nó hoạt động giống như trong trình duyệt, nhờ vào DOM. | Presentation CSS pieces of functionality. This kind of feature used to exist only in desktop applications but now it works just as well in the browser thanks to the DOM. Presentation CSS CSS Cascading Style Sheets provides a unified method for controlling the appearance of user interface elements in your web application. You can use CSS to change almost any aspect of the way the page looks from font sizes colors and spacing to the positioning of elements. In an AJAX application one very good use of CSS is to provide user-interface feedback with CSS-driven animations and transitions or to indicate portions of the page with which the user can interact with changes to color or appearance triggered for example by mouseovers . For example you can use CSS transitions to indicate that some part of your application is waiting for an HTTP request that s processing on the server. CSS manipulation figures heavily in the broader definition of the term AJAX in various visual transitions and effects as well as in drag-and-drop and edit-in-place functionality. Communication XMLHttpRequest XMLHttpRequest a JavaScript class with a very easy-to-use interface sends and receives HTTP requests and responses to and from web servers. The XMLHttpRequest class is what makes true AJAX application development possible. The HTTP requests made with XMLHttpRequest work just as if the browser were making normal requests to load a page or submit a form but without the user ever having to leave the currently loaded web page. Microsoft first implemented XMLHttpRequest in Internet Explorer 5 for Windows as an ActiveX object. The Mozilla project provided a JavaScript-native version with a compatible API in the Mozilla browser starting in version . It s also available in Firefox of course. Apple has added XMLHttpRequest to Safari since version . The response from the server either an XML document or a string of text can be passed to JavaScript to use however the developer sees fit often to .