<form name="frm">
<input name="name" type="text" id="name" placeholder="Enter Your Name" required>
<input name="number" id="number" type="text" pattern="[789][0-9]{9}" placeholder="Enter Your Mobile Number" required>
<button style="font-size: 22px;" value="submit" onClick="myFunction()" type="submit">Submit</button>
<div id="popcode"></div>
</form>
function myFunction() {
var a,b,currdate,d,n;
a= document.frm.text.value;
b=a.substring(0,2);
var currdate = new Date();
var currdate= currdate.getDate() + '' + (currdate.getMonth()+ 1) + '' + String(currdate.getFullYear()).substr(2);
var d = new Date();
var n = d.getSeconds();
document.getElementById("popcode").innerHTML =b+currdate+n;
}