HTML - Select Element

About

select is an HTML control form element used for selecting one or more value amongst a set of options.

It creates a drop-down list used in a form that will set a scalar value from a list of option.

Example

Option

Only with option has children.

For example, this HTML creates a drop-down list of colors:

<select>
  <option value="blue">Blue</option>
  <option value="yellow">yellow</option>
  <option value="red">Red</option>
  <option selected value="green">Green</option>
</select>

OptGroup

HTML - Optgroup element (Group of Option)

<form onSubmit="handleSubmit(this); return false;">
<label for="country">Choose a country:</label>
<select id="country">
    <optgroup label="Europa">
        <option>England</option>
        <option>Germany</option>
        <option>Netherland</option>
    </optgroup>
    <optgroup label="Africa">
        <option>Marroco</option>
        <option>Algeria</option>
        <option>Tunisia</option>
    </optgroup>
</select>
<button type="submit">Submit form</button>
</form>
let handleSubmit = function(form){
    console.log("The country chosen is "+form.country.value);
}

Free form

By default, there is no free form. The select element forces a selection (whereas datalist does not)

But you may add an extra input value

<label for="color">Colors:</label>
<select>
  <option value="blue">Blue</option>
  <option value="yellow">yellow</option>
  <option value="red">Red</option>
  <option selected value="green">Green</option>
</select>
  If other, please specify:
<input type="text" name="color_free" id="color_free">

Syntax

Inside a select, you may find:

  • an optgroup [optional] that group
    • option elements that defines the values.

Attribute

Multiple

Boolean attribute indicates that multiple options can be selected in the list by holding the ctrl key (Default: false)

Example:

<form onSubmit="handleSubmit(this); return false;" >
    <select id="color" name="color" multiple>
      <option value="blue">Blue</option>
      <option selected value="yellow">yellow</option>
      <option value="red">Red</option>
      <option selected value="green">Green</option>
    </select>
    <button type="submit">Submit form</button>
</form>
let handleSubmit = function(form){
    console.log("The select type is "+form.color.type);
    console.log("The number of options are "+form.color.length);
    console.log("The first value chosen is "+form.color.value);
    let formData =  new FormData(event.target);
    let colors =  formData.getAll("color");
    console.log("The value chosen are "+colors);
}
  • The result

Form

If not used in a form element, you can set the form attribute with the id of the form to associate it with the select.

Event

When the value changes, it fires an input event.

  • The HTML
<select name="crust">
  <option value="regular">Regular crust</option>
  <option selected value="deep">Deep dish</option>
  <option value="thin">Thin crust</option> 
</select>
  • The javascript
document.querySelector("select").addEventListener("input", function(){
   console.log("The input event has fired for the value: "+this.value);
});
  • Result: Select an option and see the log of values

Library

Documentation / Reference


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