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What does the html optgroup tag mean? Analysis of usage and attribute examples of html optgroup tag

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寻∝梦Original
2018-08-21 14:21:544494browse

html What does the optgroup label mean? Regarding the usage and attribute instance analysis of the html optgroup tag, this article introduces the definition and attribute examples of the html optgroup tag, as well as the usage of the html optgroup tag

html optgroup tag Definition and usage:

5b7a15bed8615d1b843806256bebea72 tag defines an option group.

The optgroup element is used to group options. When you work with a long list of options, grouping related options can make things easier.

HTML 5b7a15bed8615d1b843806256bebea72 tag example:

Group related options together through the 5b7a15bed8615d1b843806256bebea72 tag: 

<select>
  <optgroup label="Swedish Cars">
    <option value ="volvo">Volvo</option>
    <option value ="saab">Saab</option>
  </optgroup>
  <optgroup label="German Cars">
    <option value ="mercedes">Mercedes</option>
    <option value ="audi">Audi</option>
  </optgroup>
</select>

Required attributes of the html optgroup label:

label: text: Specifies a description for the option group. (Example above)

html Optional attributes of the optgroup tag:

disabled: disabled: Specifies that the option group is disabled.

HTML 5b7a15bed8615d1b843806256bebea72 The disabled attribute of the tag

The disabled attribute definition of the optgroup tag:

The disabled attribute stipulates that it is disabled This option group. Disabled option groups are neither available nor clickable.

You can set the disabled attribute to restore the user's use of the option group until certain conditions are met (such as selecting a check box). You can then use JavaScript to clear the disabled attribute so that the option group becomes available.

Disabled attribute example of optgroup tag

A disabled option group:


##

<select>
  <optgroup label="German Cars" disabled="disabled">
    <option value="mercedes">Mercedes</option>
    <option value="audi">Audi</option>
  </optgroup>
</select>

html The usage of the optgroup tag is grouped, read-only and displayed in a tree style:

In addition to the option tag in the html select tag, there is another tag called optgroup. What can it do for us?

We have already understood the meaning of point connection from the name: it is an option group, just like checkboxgroup and radiogurop, it is used for grouping;

Look at the following piece of code, while browsing When you open the browser you will see a drop down menu. But when you choose java or .Net, you can't choose.​ ​

Moreover, the style is different from that of the option tag, and the font is bold. And the drop-down menu is displayed in a tree-like style. 

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">  
<html>  
    <head>  
        <title>optgroup</title>  
        <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">  
        <meta http-equiv="description" content="this is my page">  
        <meta http-equiv="content-type" content="text/html; charset=UTF-8">  
    </head>  
    <body>  
        <select>  
            <optgroup label="Java">  
                <option value="jsp Servlet">jsp Servlet</option>  
                <option value="javaEE">javaEE</option>  
            </optgroup>  
            <optgroup label=".Net">  
                <option value="aspx">aspx</option>  
                <option value="C#">C#</option>  
            </optgroup>  
        </select>  
    </body>  
</html>

Browser support

All major browsers support the 5b7a15bed8615d1b843806256bebea72 tag.

Global attributes

The5b7a15bed8615d1b843806256bebea72 tag supports global attributes in HTML.

Event Attributes

5b7a15bed8615d1b843806256bebea72 tag supports event attributes in HTML.

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