JS - Only numeric allowed and limit character on input

Question

<input id="contact" maxlength="12" name="phone-number" id="phone" value="<?php echo $myeq["userphone"]; ?>" class="valid-empty valid-phone" data-err-msg="Phone cannot be empty." data-invalid-msg="Invalid phone number, please use number only." onkeypress='return event.charCode >= 48 && event.charCode <= 57'>