validate inputs (number, email) by using pattern & show custom error messages. suggestion: using http://parsleyjs.org/

validate-inputs.html

<!-- number is positive -->
<input type="number" pattern="[0-9]+" />

<!-- email -->
<input type="email" pattern="([a-z0-9_]+|[a-z0-9_]+\.[a-z0-9_]+)*@([a-z0-9]|[a-z0-9]+\.[a-z0-9]+)+\.([a-z]{2,4})" />

<!-- Vietnamese phone -->
<input type="tel" pattern="0[0-9]{9,10}" />

<!--
show custom error messages
suggestion: http://parsleyjs.org/
complex solution: http://stackoverflow.com/questions/13798313/set-custom-html5-required-field-validation-message
simple solution: http://stackoverflow.com/questions/10361460/how-can-i-change-or-remove-html5-form-validation-default-error-messages
-->