HTML5 Input Pattern
HTML
<form action="demo_form.asp">
<input type="text" pattern="^(https?):\/\/[^\s/$.?#].[^\s]*$" title="Three letter country code">
<input type="submit" value="ok">
</form>
<form action="demo_form.asp">
<input type="text" pattern="^(https?):\/\/[^\s/$.?#].[^\s]*$" title="Three letter country code">
<input type="submit" value="ok">
</form>