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This article mainly shows you "what are the HTML5 front-end interview questions", the content is easy to understand, clear, hope to help you solve your doubts, the following let the editor lead you to study and learn "what are the HTML5 front-end interview questions" this article.

1. The understanding of HTML semantics?

HTML semantics is to make the content of the page structured, easy for browsers, search engines to parse; without a style CSS, it is also displayed in a document format, and is easy to read; search engine crawlers rely on tags to determine the context and the weight of each keyword, which is good for SEO; to make it easier for people who read the source code to block the site for easy reading and understanding.

2. How to achieve the transparency of the parent element without affecting the transparency of the child element?

Method 1: use rgba

Method 2: add a layer of div at the same level as the parent element to load the child element, and locate the original location of the child element

3. Understanding and understanding of web standard and W3C

The web standard is to implement the structure, performance and behavior of the page independently. W3C puts forward standardized requirements for tagging.

Requirements for structure: (tag specification can improve the efficiency of page crawling by search engines, which is very helpful to SEO)

Label letters should be lowercase; labels should be closed; labels are not allowed to be nested at will

Requirements for css and js:

Try to use outreach css style sheets and js scripts to separate structure, performance and behavior, and at the same time improve page rendering speed and user experience

Style uses less interline stylesheets as much as possible, so that structure and performance are separated. The id and class naming of tags should be literal. The fewer tags, the faster loading, the higher user experience, easier code maintenance, and easier revision.

No need to change the content of the page, you can provide a printed version without the need to copy the content, improving the ease of use of the website

4. The difference between display none visibility hidden?

Display:none disappears completely and does not occupy space in the document stream, and the browser will not parse the element; visibility:hidden disappears visually, which can be understood as the effect of zero transparency, and occupies space in the document stream, and the browser will parse the element

The performance of using visibility:hidden is better than that of display:none. When display:none switches and displays, visibility, the page generates reflux (when some elements in the page need to be changed in size, layout, display, hiding, etc., and the page is rebuilt, it is called reflux. All pages need to generate a reflow when they are loaded for the first time), while the visibility switch does not cause reflux when it is displayed or not.

5. The difference between Px, em and rem

Similarities: px, em, and rem are all units of length

Similarities and differences: the value of px is fixed, and it is easy to calculate as much as you specify. The value of em is not fixed, and em inherits the font size of the parent element. Rem is calculated based on the font size of the tag HTML. The default font height of the browser is 16px. So all unadjusted browsers match: 1em=1rem=16p

So 12px=0.75em=0.75rem 10px=0.625em=0.625rem.

The above is all the contents of the article "what are the HTML5 front-end interview questions?" Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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