This chapter will introduce the 6 design principles that HTML5 needs to follow. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.
Principle 1: Avoid unnecessary complexity
html4
<!DOCTYPE html PUBLIC "-//W3C/DTD HTML 4.01//EN" " <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
html5
<!DOCTYPE html> <meta charset="utf-8">
Principle 2: Support existing content
In the following four pieces of code, only the first paragraph is correct in xhtml; in html5, all of them are Correct
<img src="foo" alt="bar" /> <p class="foo">Hello world</p>
<img src="foo" alt="bar"> <p class="foo">Hello world
<IMG SRC="foo" ALT="bar"> <P CLASS="foo">Hello world</P>
<img src=foo alt=bar> <p class=foo>Hello world</p>
Principle 3: Solve real-life problems
In HTML4, even if two block-level elements have the same link address , must also be written separately, because inline elements cannot contain block-level elements
<h2><a href="/path/to/resource">Headline text</a></h2> <p><a href="/path/to/resource">Paragraph text.</a></p>
And in html5, due to the use of the content model, elements can also contain block-level elements
<a href="/path/to/resource"> <h2>Headline text</h2> <p>Paragraph text.</p> </a>
Principle 4: Seek truth and be pragmatic
html5 has added a number of new elements, including: section, article, aside and nav, which represent a new Content model - Partition content. People have been using divs to organize content on pages in the past, but like other similar elements, divs themselves have no semantics. But section, article, aside, and nav are actually telling you clearly that this section is like another document within the document. Any content located within these elements can have its own summary, its own title, its own footer.
Principle 5: Smooth degradation
When the browser encounters an unrecognized type value, it will interpret the value of type as text
input type="number" input type="search" input type="range" input type="email" input type="date" input type="url"
Principle 6: End user first
In case of conflict, the end user takes priority, followed by the author, followed by the implementer, followed by the standard The framer, in the end, is the theoretical perfection.
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