The graceful degradation perspective
Graceful degradation focuses on building the website for the most advanced/capable browsers. Testing in browsers deemed “older” or less capable usually takes place during the last quarter of the development cycle and is often restricted to the previous release of the major browsers (IE, Mozilla, etc.).
Under this paradigm, older browsers are expected to have a poor, but passable experience. Small fixes may be made to accommodate a particular browser. Because they are not the focus, little attention is paid beyond fixing the most egregious errors.
The progressive enhancement perspective
Progressive enhancement focuses on the content. Note the difference: I didn’t even mention browsers.
Content is the reason we create websites to begin with. Some sites disseminate it, some collect it, some request it, some manipulate it, and some even do all of the above, but they all require it. That’s what makes progressive enhancement a more appropriate paradigm. It’s why Yahoo! swiftly adopted it and used it to create their Graded Browser Support strategy.
Graceful degradation 忽略次要浏览器
Progressive Enhancement 内容为中心，然后css，然后js，步步为营。
The main difference between the graceful degradation strategy and progressive enhancement is where you start your design.
- If you start with the lowest common denominator and then add features for more modern browsers for your web pages, you’re using progressive enhancement.
- If you start with the most modern, cutting edge features, and then scale back, you’re using graceful degradation.