How to restrict user to type 10 digit numbers in input element?

try this

<input type="text" name="country_code" title="Error Message" pattern="[1-9]{1}[0-9]{9}"> 

This will ensure

1. It is numeric
2. It will be max of 10 chars
3. First digit is not zero

Use maxlength

<input type="text" maxlength="10" />