Web Standards
Simply put, HTML, CSS, JavaScript are the three separate. A Web standard is not a standard, but a collection of standards. The Web page consists mainly of three parts: structure (Structure), Performance (Presentation) and Behavior (Behavior). The corresponding standards are divided into three aspects: the structure standard language mainly includes XHTML and XML, the performance standard language mainly includes the CSS, the behavior standard mainly includes the object model (such as the ECMAScript DOM), and so on.
Usability : Whether the product is easy to use, the user can complete the task, how efficient, and the user's subjective feeling in the process is very well, from the user's point of view of the product quality. Good usability means high product quality, is the core competitiveness of enterprises.
maintainability : Generally contains two levels, one is when the system problems, quickly locate and solve the problem of cost, low cost can be good maintainability. The second is whether the code is easy to understand, whether it is easy to modify and enhance the function. There are intersections where maintainability and reusability, scalability, and so on are possible. Building maintainable code is important for the long-term development of your business.
What is accessibility? It is difficult to give a strict definition. In the Web Content Accessibility Guidelines 1.0 (Web Accessibility Guide), the description of accessibility is: Web content is readable and understandable to users with disabilities. It is also noted in the Guide that improving accessibility also makes it easier for ordinary users to understand Web content. In particular, consider the following two aspects:
- The user agent must access the Web content, whether or not the user is disabled. Therefore, to improve accessibility, the first consideration is to consider a variety of user agents: Desktop browser, voice browser, mobile phone, car pc and so on. At Google, a number of disabled employees have been hired to help improve the accessibility of products.
- You also need to consider the environmental limitations of users accessing Web content. For example: Noisy environment, dark or too bright room, or hands-free and other situations. This is a higher level of accessibility requirements, to achieve, can create products in specific areas of the core competitiveness.
ways to achieve availability and accessibility
- Step up your site's functionality and test for support at the same time. Develop Web sites using "progressive enhancement" and "Smooth degradation" principles.
- Allows the user to turn off problematic enhancements.
- Provide an alternative version of the same content or feature.
- Make recommendations to your customers about the technologies that clients need to support, and give examples of which companies ' products support these technologies.
Four accessibility standards (WCAG 2.0)
- Perceptual: People can learn about Web content through the right media for themselves. For example, the blind should be allowed to listen to the page. For example, an image should have a text counterpart.
- Actionable : people can interact with Web applications or content. For example, a user should be able to interact with a site without a mouse, and navigate through a screen reader.
- understandable: users can understand page content and user interface. For example, the body should not be more complex than it needs, and the site should run in a predictable way.
- Robustness: All services provided should not be limited by the platform or the operating system. This avoids the provision of less sophisticated services that can be used by most people because of hardware/software limitations. For example, browsers on different devices can use the site together, and the navigation should be consistent.
Advantages of Web standards:
- code Efficiency: Use the most streamlined code in the HTML file, and include the style and page layout information in the CSS file. The smaller the file placed on the server, the less time it takes to download the file.
- Easy maintenance: page style and layout information is saved in a separate CSS file, and if you want to change the look of your site, you only need to make changes in a separate CSS file. The entire site unified CSS can bring great convenience.
- Accessibility: Those who have impaired eyesight in the Internet users can read the contents of the webpage to them by using the keyboard command on the screen reader. Web page files written in semantic HTML (structured and expressive HTML) make it easier for such users to navigate, and important information in Web files is more likely to be found by these users.
- device compatibility: plain HTML, no additional style information, can be reformatted for devices with different characteristics (such as screen size, etc.), only one set of additional stylesheets is required. At the same time, CSS itself allows you to specify different style sheets for different presentation and media types (such as reading pages on screen, printing Web pages, reading pages on mobile devices, etc.).
- Web crawler/Search engine: search engines use "crawlers" to parse your Web pages. Semantic HTML can be parsed more accurately and quickly to know what is important, so your page's ranking in search results will be greatly affected.
Web standards-availability, maintainability, accessibility
