Validating user input against specific rules is a common thing when we work with input fields. Without using an external validation library, we can use some built-in HTML 5 inputs to strict the value.
Specifically, the following input types force user to enter valid characters:
| Input type | Description |
|---|---|
type="color" | Only accepts a color |
type="date" | Only accepts a date |
type="email" | Only accepts a valid email address |
type="number" | Only accepts a number |
type="tel" | Only accepts a phone number |
type="url" | Only accepts a URL |
Although these input types are useful, they can't serve the cases that the input must match a given regular expression.
For example, how we can force user to enter exactly 10 digits of a phone number when using the type="tel" attribute. That's where the pattern attribute comes in.
The sample code below solves the issue mentioned earlier:
<input
type="tel"
pattern="^\d{10}$"
title="Please enter 10 digits"
/>It's recommended to use the title attribute, so users know what the correct value is.
