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Table of Contents
How to use multiple attributes
How to submit data when multiple selections
How to get selected values through JavaScript
Common precautions
Home Web Front-end HTML Tutorial HTML `select` `multiple` Attribute for Multi-Selection

HTML `select` `multiple` Attribute for Multi-Selection

Jul 22, 2025 am 01:31 AM

To implement the drop-down menu multiple selection function in HTML, 1. Add the multiple attribute to the , PHP can receive arrays through $_POST['colors'], and JavaScript can use Array.from(selectElement.selectedOptions).map to get values.

HTML `select` `multiple` Attribute for Multi-Selection

In web development, if you want users to select multiple options from the drop-down menu, the HTML select element can easily achieve this function with multiple attributes. Just add this attribute to let the user hold down Ctrl (or Command on Mac) to perform multiple selections.

HTML `select` `multiple` Attribute for Multi-Selection

How to use multiple attributes

To enable the multi-select function, just add multiple attribute to the <select></select> tag:

 <select multiple>
  <option value="option1">Option 1</option>
  <option value="option2">Option 2</option>
  <option value="option3">Option 3</option>
</select>

In this way, the browser will render a drop-down box that can be selected multiple times. Users can select multiple options by clicking and cooperating with the Ctrl key. Note that the drop-down box will become a list box style at this time, rather than the traditional drop-down menu.

HTML `select` `multiple` Attribute for Multi-Selection

How to submit data when multiple selections

When a form is submitted, multiple selected values are sent to the server as an array. For example, if you use PHP to receive data, you can obtain multiple values by:

 $selected = $_POST[&#39;selectName&#39;];
foreach ($selected as $value) {
  echo $value . &#39;<br>&#39;;
}

When processing backend, make sure the field name has [] , for example:

HTML `select` `multiple` Attribute for Multi-Selection
 <select name="colors[]" multiple>
  <option value="red">Red</option>
  <option value="blue">blue</option>
  <option value="green">Green</option>
</select>

This way the server side can correctly receive multiple values.

How to get selected values through JavaScript

If you want to use JavaScript to get multiple currently selected values, you can use the following methods:

  • Use querySelectorAll to get all selected options:
 const selectedOptions = document.querySelectorAll(&#39;select[multiple] option:checked&#39;);
const values = Array.from(selectedOptions).map(option => option.value);
console.log(values);
  • Or through HTMLSelectElement.selectedOptions property:
 const selectElement = document.querySelector(&#39;select[multiple]&#39;);
const selected = Array.from(selectElement.selectedOptions).map(opt => opt.value);
console.log(selected);

These methods can help you dynamically obtain user selection results on the front-end.

Common precautions

  • Display style differences : The appearance of the multi-select drop-down box may be slightly different under different browsers. It is recommended to customize the styles through CSS or JavaScript plug-ins if necessary.
  • Mobile compatibility : On mobile devices, the native multi-select drop-down box experience may not be good, and some devices do not even support click multi-select. If mobile support is required, it is best to use third-party components (such as Select2 or Bootstrap Multiselect).
  • Not expanded by default : If you want all options to be expanded by default when the page is loaded, additional JavaScript or CSS control is required.

Basically that's it. This function is not complicated, but it is easy to ignore details in actual development, such as how the backend receives data, mobile compatibility issues, etc., which need to be paid attention to.

The above is the detailed content of HTML `select` `multiple` Attribute for Multi-Selection. For more information, please follow other related articles on the PHP Chinese website!

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