validate phone 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: html textbox pattern mobile number

<input type="text" name="Phone Number" pattern="[7-9]{1}[0-9]{9}" 
       title="Phone number with 7-9 and remaing 9 digit with 0-9">

Example 3: phone number validation html

How about this? /(7|8|9)\d{9}/

It starts by either looking for 7 or 8 or 9, and then followed by 9 digits.