HTML attribute: readonly - HTML: HyperText Markup Language 编辑

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The Boolean readonly attribute, when present, makes the element not mutable, meaning the user can not edit the control. If the readonly attribute is specified on an input element, because the user can not edit the input, the element does not participate in constraint validation.

The readonly attribute is supported by  text, search, url, tel, email, password, date, month, week, time, datetime-local, and number<input> types and the <textarea> form control elements. If present on any of these input types and elements, the :read-only pseudo class will match. If the attribute is not included, the :read-write pseudo class will match.

The attribute is not supported or relevant to <select> or input types that are already not mutable, such as checkbox and radio or cannot, by definition, start with a value, such as the file  input type. range and color, as both have default values. It is also not supported on hidden as it can not be expected that a user to fill out a form that is hidden. Nor is it supported on any of the button types, including image.

Note: Only text controls can be made read-only, since for other controls (such as checkboxes and buttons) there is no useful distinction between being read-only and being disabled, so the readonly attribute does not apply.

When an input has the readonly attribute, the :read-only pseudo-class also applies to it. Conversely, inputs that support the readonly attribute but don't have the attribute set match the :read-write pseudo-class.

Attribute interactions

The difference between disabled and readonly is that read-only controls can still function and are still focusable, whereas disabled controls can not receive focus and are not submitted with the form and generally do not function as controls until they are enabled.

Because a read-only field cannot have it's value changed by a user interaction, required does not have any effect on inputs with the readonly attribute also specified.

The only way to modify dynamically the value of the readonly attribute is through a script.

Note: The required attribute is not permitted on inputs with the readonly attribute specified.

Usability

Browsers display the readonly attribute...

Constraint validation

If the element is readonly, then the element's value can not be updated by the user, and does not participate in constraint validation.

Example

HTML

<div class="group">
  <input type="textbox" value="Some value" readonly="readonly"/>
  <label>Textbox</label>
</div>
<div class="group">
  <input type="date" value="2020-01-01" readonly="readonly"/>
  <label>Date</label>
</div>
<div class="group">
  <input type="email" value="Some value" readonly="readonly"/>
  <label>Email</label>
</div>
<div class="group">
  <input type="password" value="Some value" readonly="readonly"/>
  <label>Password</label>
</div>
<div class="group">
  <textarea readonly="readonly">Some value</textarea>
  <label>Message</label>
</div>

Result

Examples

<fieldset>
  <legend>Checkboxes buttons</legend>
  <p><label>
    <input type="checkbox" name="chbox" value="regular"> Regular
  </label></p>
  <p><label>
    <input type="checkbox" name="chbox" value="readonly" readonly> readonly
  </label></p>
  <p><label>
    <input type="checkbox" name="chbox" value="disabled" disabled> disabled
  </label></p>
</fieldset>
<fieldset>
  <legend>Radio buttons</legend>
  <p><label>
    <input type="radio" name="radio" value="regular"> Regular
  </label></p>
  <p><label>
    <input type="radio" name="radio" value="readonly" readonly> readonly
  </label></p>
  <p><label>
    <input type="radio" name="radio" value="disabled" disabled> disabled
  </label></p>
</fieldset>

Specifications

Specification	Status	Comment
HTML Living Standard The definition of 'readonly attribute' in that specification.	Living Standard
HTML5 The definition of 'readonly attribute' in that specification.	Recommendation
HTML 5.1 The definition of 'readonly attribute' in that specification.	Recommendation

See also

• :read-only and :read-write
• <input>
• <select>