Design theory: Ensure good accessibility and usability

Common to the online blog has the wrong theory, including many friends around have agreed that "accessibility (accessibility) is for people with disabilities," the view. In fact, in the field of Internet technology is far more than that simple, summed up there are three aspects:

1. Coping with the normal browsing requirements in extreme environments;
2. Structure, performance, behavior across the terminal Cross-platform compatible support;
3. Ensure accessibility of information for people with disabilities.

web1.0 site to content-oriented, web2.0 site to function-oriented. At present, the main "pure function, content + function, pure content" three types of Web site interface form, the pattern has been basically stereotyped. Although the content-oriented web site more prominent accessibility, to feature-oriented site more prominent usability, but not to say that the main function of the site does not need to consider the accessibility.

Technology development so far, "pure function" website interface to improve usability has a large number of rich client applications, and gradually form the core competitiveness. That is to say, it is almost impossible to guarantee good accessibility and usability at the same time, so you can only use the guaranteed user friendly solution and tell me why? What to do? Gmail, for example, will default to "basic HTML" mode in disable JavaScript, and a reminder "JavaScript must be enabled if you switch to Standard view." The following figure:

But in the traditional "content + function" website interface, which is not used by rich clients as the core competence, it is possible to guarantee good accessibility and usability, just technical complexity problem. For example, Yahoo home page This famous web2.0 portal and AJAX application model, in disable JavaScript, although all interactive mode can not be used, but the function is not affected, the overall page effect remains good. The following figure:

"Pure content" website interface is information-oriented, news-type Web site content page, a large number of existing in the Internet, but also a large number of included in the search engines, such a page to ensure that accessibility more to grasp the user's core needs. For example, 163 news content page, in disable CSS situation, still can clearly identify the content of the information, on the one hand, the priority to deal with properly, on the other hand, the structure of the markup language is good. The following figure:

Speaking of disable CSS, JavaScript, a lot of peers will think of human factors, and the conclusion of the application scenario is not typical, do not consider. In fact, know how to disable high-end users must also know how to enable, really terrible is slow speed, I/O equipment failures, and other non-human factors, resulting in CSS, JavaScript can not download or parse.

Web data analysis of 50 million independent users on the Internet shows that JavaScript disabled has 1.19%, which is similar to several websites I can see. If 50 million of traffic per day, there are probably 600,000 such users.

Whether the client or server-side of the network problem, will cause data can not download, browser can not render, seriously affecting the user's browsing experience. Perhaps some people think that once the dial-up era this problem is more obvious, now resources are generally more well-off. First of all, not all of China's network has been well-off, the second is not a well-off network on health, such as our office often also because of hardware firewalls, bandwidth constraints and other causes of network failure, as well as a variety of dial-up wireless turtle speed Internet.

Especially in the spread of virus, toxic anti-virus, the browser will often appear inexplicable problems, I have encountered because the browser has been the foot of this newspaper is wrong, resulting in services can not be used, the data will not affect the work. In addition, the use of proxy server in the domestic angry green, false anger are also a lot of people, whether anyone has considered why some Web site access easy? Some difficulties?

Back five years ago, when Gmail and Flickr first became popular at home, there was no doubt that there was a severe test of the inefficiency of access. As users of the time and now practitioners, we might as well put ourselves in serious thinking, why do Gmail fault-tolerant? Why is Flickr slow and steady?

Extreme situations are not only met under extreme conditions, but uncontrollable factors are everywhere. The famous poet Tagore once said that the furthest distance in the world is not life and death, but the distance between telecommunication and Netcom, and the distance that China connects the world.