HTML flow chart: from HTML tags to web page rendering

HTML (Hypertext Markup Language) is a markup language used to create web pages. By adding different attributes and content to HTML tags, various elements of web pages can be created, including text, pictures, links, tables, etc. wait. This article will introduce the detailed process from HTML tags to web page rendering.

1. Classification and basic structure of HTML tags

HTML tags can be divided into block-level elements and inline elements. Block-level elements are usually used to display segmented content, such as paragraphs, titles, lists, etc.; inline elements are used to display part of text, such as links, emphasized text, pictures, etc. In an HTML document, a tag is a pair of keywords enclosed in angle brackets, usually consisting of a start tag and an end tag. The tag can contain some attributes, through which attributes are used to specify some characteristics of the web page element.

The basic structure of HTML tags is as follows:

<起始标签 属性1=“属性值1” 属性2=“属性值2”> 此处为标签的内容 </结束标签>

2. The process of browser rendering HTML

When the browser requests an HTML web page, it will download the web page content from the server to the local computer and convert HTML into a DOM tree structure that the browser can understand. The DOM tree is a hierarchical structure composed of a series of nodes and elements, including all elements and content in the HTML document. The browser will render HTML into a page according to the DOM tree structure and follow the following steps:

1. HTML parsing: The browser will parse all tags in the HTML document into nodes on the DOM tree and process CSS at the same time. and JavaScript and other related files.
2. Style calculation: The browser will calculate the style information of each node based on the CSS style sheet, and determine the specific location, size and other attributes of each node.
3. Layout stage: The browser will calculate the exact position of each node in the web page based on the position, size and other attributes obtained in the style calculation.
4. Drawing phase: The browser will convert all nodes into pixels on the screen and display them.
5. Reflow and redraw: When the position and size of page elements change, the browser needs to recalculate and render the page. This process is called reflow and redraw, and it affects the performance and rendering speed of the entire page.

3. Introduction to commonly used HTML tags

The following introduces some commonly used HTML tags and their attributes:

1. Text tags

(1)

~

: Indicates title tags. The smaller the number, the larger the font. It is generally used for the title of an article.

(2)

: Represents a paragraph tag, used to represent one or more paragraphs of text content in an article.

2. Style tag

(1) : Indicates an emphasis tag, and the text is bold.

(2) : Indicates emphasis on tags, and the text is italicized.

3. Picture tag

(1) : used to insert pictures, should contain two attributes: src and alt.

4. Link tag

(1): Indicates the link tag, which should contain the href attribute and link address.

5. List tag

(1)

: Represents an unordered list tag;

(2)

: Represents an ordered list tag;

(3)

1. : Represents each item in the list, each
2. must be nested in a
   or
   tag middle.

   4. Summary

   As the basic markup language for web development, HTML is an indispensable part of building web pages. Understanding the basic structure and working principles of HTML, as well as some commonly used HTML tags and their attributes, can help us build web pages better and also help us optimize web page performance.

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