HTML optimization tips you should know-HTML Tutorial-php.cn

How to improve the performance of Web pages, many developers start from many aspects, such as JavaScript, image optimization, server configuration, file compression or adjusting CSS.

It is clear that HTML has reached a bottleneck, even though it is an essential core language for developing Web interfaces. The load of HTML pages is also getting heavier and heavier. Most pages require an average of 40K of space. For example, some large websites contain thousands of HTML elements, and the page size will be larger.

How to effectively reduce the complexity of HTML code and the number of page elements. This article mainly solves this problem. It introduces how to write concise and clear HTML code from many aspects, which can make the page load faster. , and can run well on a variety of devices.

The following principles need to be followed during the design and development process:

Structural separation: Use HTML to add structure, not style content;
Keep it tidy: Add code validation tools to your workflow; use tools or style wizards to maintain code structure and format
Learn a new language: Get element structure and semantic markup.
Ensure accessibility: Use ARIA attributes and Fallback attributes, etc.
Test: Make the website run well on multiple devices and can be used emulators and performance tools.

HTML optimization tips you should know

The relationship between HTML, CSS and JavaScript

HTML is a markup language used to adjust the structure and content of the page. HTML cannot be used to modify style content, nor can you enter text content in the header tag, making the code lengthy and complex. Instead, it is more appropriate to use CSS to modify layout elements and appearance. HTML ElementThe default appearance is defined by the browser's default style sheet. For example, in Chrome, the h1 tag element will be rendered into a 32px Times bold font.

Three general design rules:

Use HTML to construct the page structure, CSS to modify the page presentation, and JavaScript to implement the page function. CSS ZenGarden demonstrates behavioral separation very well.
If it can be achieved with CSS or JavaScript, use less HTML code.
Store CSS and JavaScript files separately from HTML. This can aid caching and debugging.

The document structure can also be optimized, as follows:

Use HTML5 document type , the following is an empty file:

<!DOCTYPE html>
<html>

<head>
 <title>Recipes: pesto</title>
</head>

<body>

  <h1>Pesto</h1>

  <p>Pesto is good!</p>

</body>
</html>

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Reference the CSS file at the beginning of the document, as follows ：

<head>
  <title>My pesto recipe</title>

  <link rel="stylesheet" href="/css/global.css">
  <link rel="stylesheet" href="css/local.css">

</head>

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Using these two methods, the browser will prepare the CSS information before parsing the HTML code. This helps improve page loading performance.

Enter JavaScript code before the closing tag of the body at the bottom of the page. This will help improve the page loading speed, because the browser will load the page before parsing the JavaScript code. Using JavaScript will have a positive impact on page elements. .

<body>

  ...

  <script src="/js/global.js">
  <script src="js/local.js">

</body>

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Using Defer and async attributes, script elements with async attributes are not guaranteed to be executed in order.

Handlers can be added in JavaScript code. Never add it to HTML inline code. For example, the following code can easily lead to errors and is difficult to maintain:

index.html:

<head>
  
  ...

  <script src="js/local.js">

</head>

<body onload="init()">

  ...

  <button onclick="handleFoo()">Foo</button>

  ...

</body>

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The following way of writing is better:

index.html:

<head>

  ...

</head>

<body>

  ...

  <button id="foo">Foo</button>

  ...

  <script src="js/local.js">

</body>

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js/local.js:

init();
var fooButton =
    document.querySelector(&#39;#foo&#39;);
fooButton.onclick = handleFoo();

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Verification

One way to optimize a web page is that the browser can handle illegal HTML code . Legal HTML code is easy to debug, takes up less memory, consumes less resources, is easy to parse, renders and runs faster. Illegal HTML code makes it extremely difficult to implement responsive design.

When using templates, legal HTML code is extremely important. It often happens that templates run well alone but report various errors when integrated with other modules. Therefore, the quality of HTML code must be ensured. , you can take the following measures:

Add validation functionality to your workflow: Use validation plug-ins such as HTMLHint or SublineLinter to help you detect code errors.
Use HTML5 document type
Ensure that the hierarchical structure of HTML is easy to maintain and avoid nesting elements in the left-open state
.

<video src="foo.webm" autoplay controls>

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Format consistency makes HTML code easy to read, understand, optimize, and debug.

语义标记

语义指意义相关的事物，HTML 可从页面内容中看出语义：元素和属性的命名一定程度上表达了内容的角色和功能。HTML5 引入了新的语义元素，如

，