Html 为什么在 html5 中使用 role 属性
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why use role attribute in html5
提问by olive_tree
I have created a web page using html5.
我已经使用 html5 创建了一个网页。
I used source code from bootstrap.
我使用了 bootstrap 的源代码。
For example: role="main", role ="navigation", role = "document"etc.
例如：role="main"，role ="navigation"，role = "document"等。
If I remove these attribute from my code, page didn't any change.
如果我从我的代码中删除这些属性，页面没有任何变化。
So I want to know: what is the purpose of "role" attribute?
所以我想知道：“角色”属性的目的是什么？
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link href='http://fonts.googleapis.com/css?family=Raleway:900,500,600,200,400,700' rel='stylesheet' type='text/css'>
<title>Layout</title>
<!-- Bootstrap core CSS -->
<link href="css/bootstrap.min.css" rel="stylesheet">
<link href="css/style.css" rel="stylesheet">
</head>
<body role="document">
<!-- Fixed navbar -->
<div class="navbar" role="navigation">
<div class="container">
<div class="navbar-header">
<h1><img src="img/logo.png" /></h1>
</div>
</div>
</div>
<div class="container theme-showcase" role="main">
<!-- Main jumbotron for a primary marketing message or call to action -->
<div class="container">
<div class="banner-div">
<img src="img/banner.png" class="banner"/>
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<span class="comments"><i>by</i> <a>JOHN WOO</a> <i> - 10 Commments</i></span><br/>
</div>
<div class="col-md-4 pull-right">
<div class="input-group">
<input type="text" class="form-control search-input-box" placeholder="Search..." />
<span class="input-group-addon glyphicon glyphicon-search"></span>
</div>
</div>
</div>
<hr class="hr-style"/>
<p class = "header-pgf">
Text, navigation, and tables, oh, my! What's a responsive web designer to do? How can you confine your design to as few major breakpoints as possible? Where and when will you sketching? Is it possible to sketch on actual devices, and what are the accessibility implications of doing so? The answers to these and other profound questions will be found in this exclusive excerpt from Chapter 7 of Responsive Design Workflow, Stephen Hay's new book, available now from New Riders.
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<h2>From the Blog</h2>
<p class="pgf-header">Maps Should Be Crafted.Not "Plugged In"></p>
<p>Web designers: erase the line between "the map" and "the content" by harnessing the power of open-source Leafler and your own fresh creative thinking. In the tradition of ALA's recent "Hack Your Maps." Happy Cog's Brandon Rosage shares how to make location a central aspect of the content experience-not just a visual aid.</p>
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<p class="md-3">Amazon Web Services Introduces a New API</p>
<p>Amazon Web Services Identity and Access Management(IAM) is expanding to support web identity federation. Developers can integrate Amazon.com, Facebook, or Google odentity into their app by using the new AWS Security Token Services(STS) API, AssumeRoleWithWebIdentity. to request temporary security credentials.</p>
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回答by olive_tree
It provides support for ARIA (Accessible Rich Internet Applications) which allows to specify even more semantic richness in documents.
它提供对 ARIA（可访问的富互联网应用程序）的支持，允许在文档中指定更多的语义丰富性。
You can add role="search" to your search form, role="banner" to your masthead, and role="contentinfo" to your page footer. There's a full list of values in the ARIA specification at http://www.w3.org/TR/wai-aria/roles#role_definitions.
您可以将 role="search" 添加到搜索表单，将 role="banner" 添加到标头，将 role="contentinfo" 添加到页脚。在http://www.w3.org/TR/wai-aria/roles#role_definitions 上有 ARIA 规范中的完整值列表 。
Basically you don't have to add them, but its better if you do as it provides more context for your page. More discussed at A List Apart.
基本上你不必添加它们，但如果你这样做会更好，因为它为你的页面提供了更多的上下文。更多讨论在A List Apart。
回答by Kheema Pandey
The new structural elements in HTML5 will be very useful to assistive technology. Instead of creating “skip navigation” links, all we need to do is use the nav element correctly. This will allow screen reader users to skip past navigation without us having to provide an explicit link.
HTML5 中的新结构元素将对辅助技术非常有用。我们需要做的不是创建“跳过导航”链接，而是正确使用导航元素。这将允许屏幕阅读器用户跳过导航而无需我们提供明确的链接。
Twitter Bootstrap uses like <nav role="navigation">. So Bootstrap take consider not only normal browser but also take care of screen reader browsers.
Twitter Bootstrap 使用像<nav role="navigation">. 所以 Bootstrap 不仅要考虑普通浏览器，还要考虑屏幕阅读器浏览器。
Note:By including Roleattribute you are making your website more accessible and its good practice to use this Roleattribute.
注意：通过包含Role属性，您可以使您的网站更易于访问，并且是使用此Role属性的良好做法。
