Unveil the mystery of HTML 5 working draft


The World Wide Web Consortium (W3C) released a draft specification for HTML 5, the first major revision of HTML 4 since it was released more than a decade ago During this period, as developers gradually transplant their applications to the web, it has developed from a major static media to an interactive application with rich media content The purpose of HTML 5 is to reflect such changes
JavaScript 5.0 takes a lot of new features into account by developers These contents can be used to associate with corresponding HTML elements, including:
1 / 2D drawing API, which can be used on a new canvas element to present images, game graphics or other running visual graphics
2 / an API that allows web applications to register themselves as a protocol or MIME type
3 / an API that introduces a new caching mechanism to support offline web applications
4 / an API that can play video and audio. You can use new video and audio elements
5 / a history API, which can disclose the history of browsing and allow the page to better support the back button in Ajax applications after adding it
6 / cross document messaging, which provides a way for documents to communicate with each other regardless of their source domain. 7 / to some extent, this design is to prevent cross site scripting attacks
8 / an API that supports drag and drop operations, which can be associated with the draggable feature
9 / an API that supports editing operations, which can be associated with a new global contentable feature
10 / a new network API that enables web applications to communicate with each other on the local network and maintain two-way communication on their source servers
The key / value pair of JavaScript API is used to realize the persistent storage of the client, and the embedded SQL database is supported at the same time
It greatly eliminates the need for new events to be sent to the source server through the. Event element, which can greatly eliminate the need for the persistence of events in the remote application
At the same time, HTML 5 also introduces many new presentation elements to support common page components, such as headers, footers, figures, dialog and navigation In addition, there is a new DataGrid element that supports interactive tables and trees, a datalist element for combo boxes, and a progress feature that can show the completion of a long-running task At the same time, page tags supporting RSS feeds are added
For forms, the type type of input element includes new support for date, time, email and URLs. In this way, the browser can provide user interface elements, such as a date selector of calendar or integration with user address book, and submit data to the server in a defined format
HTML 5 also dropped support for some well – known features One of the most striking is the abandonment of the support for frames, which has long been considered to undermine the accessibility and usability of web pages It is worth noting that even if the browser fully supports the HTML 5 standard, it will continue to support these abandoned features, because support for older versions of HTML will last for many years
HTML 5 was developed under the guidance of the W3C HTML working group, which was established in March 2007 The operation of the working group is fully open, with nearly 500 participants including members from apple, Google, IBM, Microsoft, Mozilla foundation, Nokia and opera
“There is no doubt that HTML is a very important standard,” said Tim Berners Lee, director of the W3C, the author of the first HTML version “I am glad to see that the developer community, including browser providers, are committed to creating the best development track of the web. It is a difficult task to integrate the ideas of so many people. The challenge we face is to find a balance between innovation and success, ideal and pragmatism.”
HTML 5 will gradually replace HTML 4, but the final determination of HTML 5 specification still has a long way to go The current plan is to use it as a candidate for recommendation during 2009, and then implement it as the final official version in September 2010
By Charles humble
Translator Zhang Yi