validation for mobile number in html code example

Example 1: how to validate mobile number in html form

<div>
  <label for="phone">Enter your phone number:</label>
<input type="tel" id="phone" name="phone"  pattern="+94[7-9]{2}-[0-9]{3}-[0-9]{4}" value="+94">
 </div>

Example 2: add html validation to mobile number

<input type="text" pattern="[789][0-9]{9}">