Hướng dẫn what is a rule in html? - quy tắc trong html là gì?

Last update on August 19 2022 21:51:12 (UTC/GMT +8 hours)

rules

The purpose of the HTML rules attribute is to specify which rulings (between rows and columns) are to be shown in a table.

Supported elements

HTML rules attribute supports table element.

Syntax

.....

Type of value

rules.

Value

Values Description
all All rulings are shown.
cols Only column rulings are shown.
groups Only group rulings are shown.
none No rulings are shown.
rows Only row rulings are shown.

Default value

Default value of HTML rules attribute is all

Supported doctypes

HTML 4.01 strict, HTML 4.01 transitional, HTML 4.01 frameset.

Example of HTML rules attribute with table element





Example of HTML rules attribute with  table element


   
   
   

Result

Hướng dẫn what is a rule in html? - quy tắc trong html là gì?

View this example in a separate browser window

Example of HTML rules attribute with table element

Previous: HTML rowspan attribute
Next: HTML scheme attribute

on September 29, 2003, 12:22 PM PDT

Basic HTML rules

Before you begin building your page, you should brush up on some basic HTML rules. Here's some helpful information to get you started.


By Fred Dekker and Donald St. John


Before you begin building your page, you’ll need to decide on a basic page layout. To do this, just sit down with some old-fashioned paper and a pencil and start sketching, blocking out the page’s elements. You may be itching to get coding, but by drawing your site out first you can rearrange designs to your heart’s content without having to code and recode.

Once you’ve settled on the organization of your site, it’s time to begin creating your pages with HTML tags–the instructions that surround material such as text, images, and links to other pages and tell the viewer’s Web browser how to display them. If you want an image to show up on the left side of the page, a certain word to appear bold, or another word to link to an outside resource, you’ll use HTML tags to do it.

There are five important rules for coding with HTML tags.

  1. Tags are always surrounded by angle brackets (less-than/greater-than characters), as in .
  2. Most tags come in pairs and surround the material they affect. They work like a light switch: the first tag turns the action on, and the second turns it off. (There are some exceptions. For instance, the
    tag creates a blank line and doesn’t have an “off switch.” Once you’ve made a line break, you can’t unmake it.)
  3. The second tag–the “off switch”–always starts with a forward slash. For example, you turn on bold with , shout your piece, and then go back to regular text with .
  4. First tag on, last tag off. Tags are embedded, so when you start a tag within another tag, you have to close that inner tag before closing the outer tag. For instance, the page will not display properly with the tags in this order:

    </code>Your text<code></HEAD>.

    The correct order is:

    </code>Your text<code>.

  5. Many tags have optional attributes that use values to modify the tag’s behavior. The
    
    
    
    
    Example of HTML rules attribute with  table element
    
    
    
       
       
       
    0 (paragraph) tag’s
    
    
    
    
    Example of HTML rules attribute with  table element
    
    
    
       
       
       
    1 attribute, for instance, lets you change the default (left) paragraph alignment. For example,
    
    
    
    
    Example of HTML rules attribute with  table element
    
    
    
       
       
       
    2 centers the next paragraph on the page.

Remember, too, that HTML is always evolving, and older browsers often don’t support the newest tags. When a browser encounters an HTML tag it doesn’t understand, it will usually ignore both the tag and the material the tag affects. This way, the newest elements will appear to viewers with newer browsers without causing problems for viewers using older browsers, who will only see material their browsers recognize. On the downside, browsers treat coding errors like unfamiliar code. If you’ve made a mistake while building your page, you won’t necessarily see an error message; you might just see nothing at all. You should always closely check all of your pages in a browser to make sure that everything that’s supposed to be there appears properly. We also recommend looking at your pages in more than one version of Navigator and Internet Explorer (on both PC and Mac platforms, if possible) to make sure everything looks the way you intended, because not every browser type or version behaves the same way.

A great way to learn about more complicated HTML is to look over the shoulders of other Web page creators. If you see a Web site you like, just view the page’s source to see how it was done. You should never just copy another builder’s design, but most developers do borrow inspiration from other sites. Methods for viewing source vary by browser, but it’s usually as simple as selecting Page Source or Source from the View menu. (Warning: Don’t try this trick with CNET pages! Our Web pages are composed of extremely complex HTML; many incorporate Java, JavaScript, and other technologies as well. Stick with viewing source code on fairly simple sites until you’re more familiar with Web building.) When viewing source code, you’ll sometimes see organizational comments from the page’s author near the top of (or scattered throughout) the file. These comments are inserted with the





Example of HTML rules attribute with  table element


   
   
   
3 or




Example of HTML rules attribute with  table element


   
   
   
4 tag and often contain useful information for those who view them. For a simple exercise in reading source code, try printing a well-commented Web page from your browser and then printing the source code of that page. Compare the two documents side by side, using the author’s comments to match sections of code with the visual elements they represent. You’ll soon be able to zero in on specific lines of code to understand how to achieve individual effects.

Fred Dekker là một trong những người sáng lập của H.E.L.P. Cộng đồng, một nguồn tài nguyên trực tuyến để bắt đầu webmasters.
Community, an online resource for beginning Webmasters.

Donald St. John là quản trị trang web sáng lập tại tạp chí PC Games.

  • Phần mềm doanh nghiệp

Quy tắc trong CSS là gì?

Quy tắc CSS là nhóm của một hoặc nhiều thuộc tính CSS được áp dụng cho một hoặc nhiều phần tử HTML đích.Quy tắc CSS bao gồm bộ chọn CSS và một tập hợp các thuộc tính CSS.Bộ chọn CSS xác định những phần tử HTML nào để nhắm mục tiêu với quy tắc CSS.a grouping of one or more CSS properties which are to be applied to one or more target HTML elements. A CSS rule consists of a CSS selector and a set of CSS properties. The CSS selector determines what HTML elements to target with the CSS rule.

Một quy tắc được đặt trong mã hóa là gì?

Một bộ quy tắc là một nhóm các quy tắc phân tích mã xác định các vấn đề được nhắm mục tiêu và các điều kiện cụ thể cho dự án đó.Ví dụ: bạn có thể áp dụng một bộ quy tắc được thiết kế để quét mã cho API có sẵn công khai.Bạn cũng có thể áp dụng một bộ quy tắc bao gồm tất cả các quy tắc có sẵn.a grouping of code analysis rules that identify targeted issues and specific conditions for that project. For example, you can apply a rule set that's designed to scan code for publicly available APIs. You can also apply a rule set that includes all the available rules.

Một quy tắc được đặt ra cho một tiêu đề trong HTML là gì?

Các tiêu đề HTML được xác định với các thẻ TO.Xác định tiêu đề quan trọng nhất.Xác định tiêu đề ít quan trọng nhất.

to

tags.

defines the most important heading.

defines the least important heading.

Việc sử dụng bộ quy tắc là gì?

Quy tắc CSS được sử dụng để áp dụng một tập hợp các thuộc tính với một số giá trị xác định cho phần tử hoặc một tập hợp các phần tử cụ thể được sử dụng trong trang HTML.to apply a set of properties with some define values for the element or a specific set of elements that are used in the HTML page.