Detailed explanation of graphic code for drop-down list selection in HTML

Drop-down list in HTML:

Html code

<select>  
  <option value ="1">Volvo</option>  
  <option value ="2">Saab</option>  
  <option value="3">Opel</option>  
  <option value="4">Audi</option>  
</select>

where select is to display a drop down list (drop down list), option is the item in the drop down list, and the text content of option is the value displayed on the page in the drop down list item, and value is the value that actually needs to be submitted to Server value.
The display effect is as follows:


More complex drop-down list:

Html code

<select>  
  <optgroup label="Swedish Cars">  
    <option value="1">Volvo</option>  
    <option value="2">Saab</option>  
  </optgroup>  
  <optgroup label="German Cars">  
    <option value="3">Mercedes</option>  
    <option value="4">Audi</option>  
  </optgroup>  
</select>

This drop-down list contains an "item group", which cannot be selected. Yes, use the label tag to mark the literal content. What really works is the value attribute.
Look at this drop-down list containing "Project Group"


Parameters in option: selected ="selected"
If you need to open the page, an option will be selected by default. You need to use the selected parameter:

Html code

<select>  
  <option value="1">Volvo</option>  
  <option value="2">Saab</option>  
  <option value="3" selected="selected">Mercedes</option>  
  <option value="4">Audi</option>  
</select>

Parameters in option: disabled="disabled"
If you need to disable an item but don’t want to hide it, you can use the disabled attribute

Html Code

<select>  
  <option value="1">Volvo</option>  
  <option value="2">Saab</option>  
  <option value="3" disabled="disabled">Mercedes</option>  
  <option value="4">Audi</option>  
</select>

Parameters in option: title
If you need to place the mouse on an item When uploading, a prompt is given, you can use the title attribute

Html code

<select>  
  <option value="1">Volvo</option>  
  <option value="2">Saab</option>  
  <option value="3">Mercedes</option>  
  <option value="4" title="Audi, your best choice!">Audi</option>  
</select>

##In fact, title Can also be used in many other HTML tags!
##

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