HTML Note (i): Docutype

1, the role of Docutype?

Write a page The first thing is to write <! DOCTYPE Html>

　　Function: Declares the parsing type (document.compatmode) of the document and avoids the browser's use of weird mode.

　　Document.compatMode:BackCompat: Weird mode, the browser uses its own weird mode to parse the rendered page, (default).

　　Document.compatmode: css1compat: Standard mode, browser using the standard analysis rendering page.

This property will be recognized and used by the browser, but if your page does not have a DOCTYPE declaration, the Compatmode default is Backcompat. When the browser parses the rendered page in its own way, the different styles are displayed in different browsers, and compatibility issues are likely to occur.

　　If you add <! to your page DOCTYPE html> So, then it is equivalent to open the standard mode, then the browser will have to be honest in accordance with the standards to parse the rendering page, so that your page in all browsers display is a look. This is <!. The role of DOCTYPE html>.

2. How to use

<! DOCTYPE html>, there is no compatibility problem, and not case-sensitive!

HTML Note (i): Docutype