HTML attribute: required

The Boolean required attribute, if present, indicates that the user must specify a value for the input before the owning form can be submitted.

The required attribute is supported by text, search, url, tel, email, password, date, month, week, time, datetime-local, number, checkbox, radio, file, <input> types along with the <select> and <textarea> form control elements. If present on any of these input types and elements, the :required pseudo class will match. If the attribute is not included, the :optional pseudo class will match.

The attribute is not supported on, or relevant to, range and color input types, as both have default values. Type color defaults to #000000. Type range defaults to the midpoint between min and max — with min and max defaulting to 0 and 100 respectively in most browsers if not declared. required is also not supported on the hidden input type — users cannot be expected to fill out a hidden form field. Finally, required is not supported on any button input types, including image.

In the case of a same named group of radio buttons, if a single radio button in the group has the required attribute, a radio button in that group must be checked, although it doesn't have to be the one on which the attribute is applied. To improve code maintenance, it is recommended to either include the required attribute in every same-named radio button in the group, or else in none.

In the case of a same named group of checkbox input types, only the checkboxes with the required attribute are required.

Because a read-only field cannot be changed, required does not have any effect on inputs with the readonly attribute also specified.

When including the required attribute, provide a visible indication near the control informing the user that the <input>, <select> or <textarea> is required. In addition, target required form controls with the :required pseudo-class, styling them in a way to indicate they are required. This improves usability for sighted users. Assistive technology should inform the user that the form control is mandatory based on the required attribute, but adding aria-required="true" doesn't hurt, in case the browser / screen reader combination does not support required yet.

If the element is required and the element's value is the empty string, then the element is suffering from valueMissing and the element will match the :invalid pseudo class.

Provide an indication to users informing them the form control is required. Ensure the messaging is multi-faceted, such as through text, color, markings, and attribute, so that all users understand the requirements whether they have color blindness, cognitive differences, or are using a screen reader.

• validityState.valueMissing
• :required and :optional
• <input>
• <select>