Accept a four-digit postal code, and nothing else.
What to build
One text input with a rule.
Requirements
- An input named
code, labelledPostal code. required.- A
patternthat accepts exactly four digits. - A
titlecontaining the worddigits.
Constraints
Use a text input, since a postal code is not a quantity.
Example
1207 is valid. 12a7 and 12070 are not.
Why it works
pattern must match the entire value, so one short pattern rules out everything except four digits.
Hints
Hint 1
Square brackets list allowed characters. Curly brackets say how many.
Hint 2
Remember required, because an empty value passes a pattern.
Hint 3
A title tells people the format.
Solution
Show one correct solution (try it yourself first)
<form>
<label for="c">Postal code</label>
<input id="c" name="code" required pattern="[0-9]{4}" title="Exactly 4 digits, like 1207">
<button>Save</button>
</form>