Required fields and input constraints help ensure that users provide valid and complete information.
HTML provides built-in attributes to control what users can enter into form fields.
The required Attribute
The required attribute makes a field mandatory.
Users cannot submit the form unless this field is filled.
If the user tries to submit without filling this field, the browser shows a validation message automatically.
Minimum and Maximum Length
The minlength and maxlength attributes control the number of characters a user can enter.
These attributes are useful for usernames, passwords, and short text fields.
Minimum and Maximum Values
For numeric fields, min and max define the allowed range of values.
This ensures that users can only enter numbers within the defined range.
The step Attribute
The step attribute controls the interval between allowed numbers.
This allows only numbers like 0, 5, 10, 15, and so on.
Why Input Constraints Matter
They prevent invalid data from being submitted.
They improve user experience and reduce backend validation errors.
Practice Task
Create a form with:
- A required name field
- A username with length constraints
- An age field with min and max values
What You Will Learn Next
In the next lesson, you will learn how to validate input formats using patterns and built-in types.