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Write high-performance HTML applications
- 高洛峰Original
- 2017-02-28 13:14:141302browse
How can you improve web page performance?
Most developers will optimize through JavaScript and images, through server configuration, compressing files and merging files - even adjusting CSS (merging small images).
Poor HTML is always ignored, even though it has always been the core language of the Internet.
HTML is getting bigger and bigger. Each HTML page of the top 100 websites is mostly around 40K. Amazon and Yahoo use thousands of HTML pages. On the main page of youtube.com, there are as many as 3,500 HTML elements.
Reducing the complexity of HTML and the number of elements on a page does not significantly improve parsing time - but HTML is a critical factor in the success of building extremely fast web pages that adapt to different devices.
In this article, you will learn how to write concise and clean HTML, allowing you to create a website that loads quickly and supports multiple devices, and will be easy to debug and maintain.
There is no one way to write code - especially HTML. This is just a general experience, but it is not the only right choice.
HTML, CSS and JavaScript
HTML is a markup language used to represent structure and content.
HTML should not be used to display styles and styles. Don’t put text in title tags (h1~h6) to appear “bigger” or use blockquotes elements just for indentation. Instead, use CSS to change the appearance and layout of elements.
The default appearance of HTML elements is achieved through the browser's default style: Firefox, Internet Explorer and Opera are all different. For example, in Chrome the h1 element is rendered to a size of 32px by default.
Three basic principles:
Use HTML to express structure, and CSS to express different styles and themes. JavaScript to respond to user actions.
Use HTML, CSS when necessary, and JavaScript when necessary. For example: In many cases, you might use HTML forms for validation and CSS or SVG for animations.
Separate CSS and JavaScript from your HTML code. Making them cacheable makes the code easier to debug. In production, CSS and JavaScript can be minified and merged and should be included as part of your Build system. Note* See JavaScript Construction (Compilation) System Competition
Document document structure
Use HTML5 document type:
<!DOCTYPE html> <html> <head> <title>Recipes: pesto</title> </head> <body> <h1>Pesto</h1> <p>Pesto is good!</p> </body> </html>
At the top of the page Reference the CSS file internally, such as in the head element:
<head> <title>My pesto recipe</title> <link rel="/css/global.css"> <link rel="css/local.css"> </head>
In this way, the browser can preload the style before parsing the HTML without rendering a confusing page layout.
Place JavaScript at the very bottom of the page, before the body is closed. This will improve page rendering time because the browser can render the page before the JavaScript is loaded:
<body> ... <script src="/js/global.js"> <script src="js/local.js"> </body>
Add event handling in JavaScript. Don't add it in HTML. This is very difficult to maintain, such as:
index.html: <head> ... <script src="js/local.js"> </head> <body onload="init()"> ... <button onclick="handleFoo()">Foo</button> ... </body>
This is much better:
<head>
...
</head>
<body>
...
<button id="foo">Foo</button>
...
<script src="js/local.js">
</body>
js/local.js:
init();
var fooButton =
document.querySelector('#foo');
fooButton.onclick = handleFoo();Legal HTML
A major factor in the success of web pages is that browsers can handle invalid HTML. Browsers also have some standardized rules for how to render invalid code.
However, this is no reason for you to let it go. Valid HTML is easier to debug, tends to have smaller file sizes, is faster, and uses fewer resources because it renders faster. Invalid HTML makes responsive design difficult to implement.
It is especially important to write valid HTML when using templates.
Validate HTML in your BUILD system: Use validation plugins such as HTMLHint and SublimeLinter to check the syntax of your HTML.
Use HTML5 document type.
Be sure to keep your HTML hierarchical: nest elements correctly and make sure there are no unclosed elements. It helps debuggers add comments.
<p id="foobar"> ... </p> <!-- foobar ends -->
Please be sure to add a closing tag after the non-self-closing element. For example, the following will also work:
<p>Pesto is good to eat... <p>...and pesto is easy to make.
But the following will work Avoid mistakes and make paragraph hierarchy more obvious:
e388a4556c0f65e1904146cc1a846beePesto is good to eat...94b3e26ee717c64999d7867364b1b4a3
e388a4556c0f65e1904146cc1a846bee...and pesto is easy to make .94b3e26ee717c64999d7867364b1b4a3
The items element (li) does not have to be closed. Some very smart programmers will write it like this. However, the list element (ul) must be closed.
<ul> <li>Basil <li>Pine nuts <li>Garlic </ul>
One thing you must pay attention to is the video and audio elements. They are not self-closing:
<!-- 错误: liable to cause layout grief --> <video src="foo.webm" /> <!-- 正确 --> <video src="foo.webm"> <p>Video element not supported.</p> </video>
Instead, the HTML page will become cleaner by removing unnecessary code
There is no need to add for self-closing elements "/", like img, etc.
Setting attributes has no value. If no attributes are added (in this case, it will not play automatically and there is no control control),
Video, It does not have any attributes
<video src="foo.webm">
The following two are better
<video src="foo.webm" autoplay="false" controls="false"> <video src="foo.webm" autoplay="true" controls="true">
This one is more readable
<video src="foo.webm" autoplay controls>
The stylet and script tags do not require the type attribute; the default is css and javascript
It is better to optimize the protocol address (remove http or https, it will Automatically configured according to the current protocol)
<a href="//en.wikipedia.org/wiki/Tag_soup">Tag soup</a>
增强可读性，如，第一眼看上去就像是个标题
<h2><a href="/contact">Contact</a><h2>
而这种则像个链接
6feca578864c89f7badd9f8f3b8a12d9c1a436a314ed609750bd7c7d319db4daContact473f0a7621bec819994bb5020d29372a5db79b134e9f6b82c0b36e0489ee08ed
应该使用小写
<A HREF="/">Home</A>
大小写混合看上去更恶心
<H2>Pesto</h2>
语义标记
“语义”意思是跟含义相关
HTML应该标记有意义的内容：元素和描述的内容相符。
HTML5引入了一些新的‘语义元素’像 1aa9e5d373740b65a0cc8f0a02150c53, c37f8231a37e88427e62669260f0074d 和 c787b9a589a3ece771e842a6176cf8e9。
使用正确的元素表达正确的内容对于可访问性是有帮助的。
使用4a249f0d628e2318394fd9b75b4636b1c1a436a314ed609750bd7c7d319db4da,684271ed9684bde649abda8831d4d355代表标题， ff6d136ddc5fdfeffaf53ff6ee95f185或c34106e0b4e09414b63b2ea253ff83d6代表lists
注意23c3de37f2f9ebcb477c4a90aac6fffd的标题应该以4a249f0d628e2318394fd9b75b4636b1开始
使用1aa9e5d373740b65a0cc8f0a02150c53, c37f8231a37e88427e62669260f0074d, c787b9a589a3ece771e842a6176cf8e9 and 15221ee8cba27fc1d7a26c47a001eb9b
使用e388a4556c0f65e1904146cc1a846bee写正文
使用907fae80ddef53131f3292ee4f81644b 和 8e99a69fbe029cd4e2b854e244eab143 代替 5a8028ccc7a7e27417bff9f05adf5932 和 a4b561c25d9afb9ac8dc4d70affff419 表示强调
表单使用2e1cf0710519d5598b1f0f14c36ba674元素，input 类型
混合文字和元素会导至布局的问题
<p>Name: <input type="text"></p>
最好用下面的表示
<p><label>Name:</label><input type="text"></p>
布局
HTML应该使用有意义的组织结构，而不是通过样式来实现。
使用e388a4556c0f65e1904146cc1a846bee元素代表文本，而不是用来布局。
避免使用0c6dc11e160d3b678d68754cc175188a来换行，使用块级元素和CSS来代替。
避免使用水平分隔线f32b48428a809b51f04d3228cdf461fa。使用CSS的border样式来控制。
不要使用不必要的p。W3C对p的定义是排序的是最后一个元素。
要了解哪些元素是块级元素，避免在p中放置不必要的块级元素。将一个list放到p中是没有必要的。
不要使用table来布局。
Flex box是被广泛推荐的，能用就用吧。
使用CSS的padding和margin，理解盒子模型。
CSS
这篇文章是关于HTML的，但是这里有一些基本的CSS小贴士。
避免内嵌的CSS。出于性能考虑，CSS可以在BUILD时内嵌到你的网页中。
避免ID出现重复。
如果你想对多个元素应用某个样式，那么请使用class，在父级元素上使用class比在子级上好：
<!-- 有点笨 :( --> <ul> <li class="ingredient">Basil</li> <li class="ingredient">Pine nuts</li> <li class="ingredient">Garlic</li> </ul> <!-- 更好 :) --> <ul class="ingredients"> <li>Basil</li> <li>Pine nuts</li> <li>Garlic</li> </ul>
可访问性
使用语义元素
提供向后兼容
在链接上添加title属性，而且应该避免与link文本出现相同的内容
在输入元素上添加type和placeholder属性
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