看到一篇文章的笔记
- sectioning elements: 
<nav><aside><article><section><body> - when to use 
- once per navigation block
 - sub-navigation in 
<nav>element doesn’t need to be wrapped in a second<nav>element 
 - a 
<nav>is unnecessary around a search form - don’t use word “nav” or “navigation” in the label
 - a 
<nav>doesn’t have to be a list of links 
- when to use 
 <aside>should not inside an<aside>
- difference between 
<article>and<section><article>is like B(Block) in BEM while<section>is like E(Element)<article>stores self-contained content which makes sense when placed in a different context<section>is a sub-section that requires context from its parent sectioning element
 - comments sections should be wrapped in an 
<article> 
- difference between 
 - don’t wrap div for a section 
<div>has no semantic meaning- useful for the sake of styling purposes
 
 - header and footer
- don’t put header or footer inside header or footer
 
 - no side bars or navigation in it
 - one 
<main>element on page visible 
- labeling sections —— one method a time 
- add an aria-label attribute (cannot translate language)
 - add a 
<h#>element - use an 
aria-labelledbyattribute