Aceptar códigos postales en HTML
<label>ZIP Code</label><input type="text" pattern="[0-9]{5}" title="Five digit zip code" />
Unsightly Unicorn
<label>ZIP Code</label><input type="text" pattern="[0-9]{5}" title="Five digit zip code" />[1-9][0-9]{3}\s?[a-zA-Z]{2}