HTML and CSS Reference
Indicating Required Values
In the survey form, Alice has indicated that the custname , email , and receipt ields
all must be completed for the survey to be valid. If any of those fields are left blank, she
wants the browser to notify the user of the missing data and cancel the submission. You
can indicate that a field is required by adding the following required attribute to the
You can turn off validation
by adding the attribute
to the form element.
If a required field is left blank and the submit button is clicked, the browser will can-
cel the submission and display an error message.
Validating Field Values
• To indicate that a field is required, add the required=”required” attribute to the
• To validate an e-mail address, set the data type to email . To validate a Web address,
set the data type to url .
• To validate that a text input box follows a character pattern, add the attribute
pattern=” regex ”
where regex is a regular expression that defines the character pattern.
To see how validation works with HTML5, add the required attribute to the
custname , email , and receipt fields.
To apply and test the required attribute:
1. Return to the survey.htm file in your text editor.
2. Add the attribute required=”required” to the input element for the custname
field at the top of the form.
3. Scroll down to the input element for the email field and then add the attribute
4. Go to the receipt field and then add the attribute required=”required” to the
input element. Figure 6-67 highlights the newly added code.