About
This page is about form validation in HTML.
The javascript counterpart is called the constraint validation API 1).
In short, you set standard HTML attributes that constrain the possible value of form elements.
Example
Check email
List of validation rules
- required
- min
- max
- minLength
- maxLength
- pattern
- validate
Limitations
HTML validation has its limitations.
- it only works in the browser (not React Native, …)
- it's hard/impossible to show custom error messages to our user.
Function
- form.checkValidity() - Returns true if the form's controls are all valid; otherwise, returns false.
- form.reportValidity() - Returns true if the form's controls are all valid; otherwise, returns false and informs the user.