regex for input type pattern code example

Example 1: 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 2: regex on input

<form>
 <label for="username">Username <i>(letters and numbers only, no  punctuation or special characters)</i></label><br>
 <input name="username" id="username" pattern="[A-Za-z0-9]+">
</form>