JSFiddle - React, Tailwind, and code Playground

HTML

<html>
<head>
  <head>
    <body>
      <input type="number" id="myNumber" onchange="ax(this)">
    </body>

</html>
<script>
var perv_num=0;
function ax(z)
{
alert("ding dong");
debugger;
let def;
let mul=10;
let valu;
let valucopy=parseInt(z.value);
let frst;
valucopy=((valucopy+100)%100);
 if (parseInt( z.value)<100) {
document.getElementById("myNumber").value="";
document.getElementById("myNumber").value=100;
}
else if(parseInt( z.value)<perv_num)
{
  def=parseInt( z.value.length);
  mul=Math.pow(mul,def-1);
   frst=(parseInt(z.value[0])*mul);
   document.getElementById("myNumber").value="";
   document.getElementById("myNumber").value=frst;
}
else if(valucopy  ==0){
document.getElementById("myNumber").value="";
document.getElementById("myNumber").value=parseInt( z.value)+100;
   }

else{
def=parseInt( z.value.length);
mul=Math.pow(mul,def-1);
frst=(parseInt(z.value[0])*mul);
valu=Math.abs( parseInt(z.value)-frst);
valu=100-valu;

var number=(parseInt(z.value)+valu);
document.getElementById("myNumber").value="";
document.getElementById("myNumber").value= number;

}
perv_num=parseInt( z.value);
}
</script>