JSFiddle - React, Tailwind, and code Playground

HTML

<input id ="bb" value="23" type='text'><input id='pay' value='check'>

JavaScript

document.querySelector('#bb').onload = function(){	
    var source = document.querySelector('#bb').value;
    document.getElementById("bb").value = addZero(source);

   	
}
function addZero(source){
	var text = source + '';
    
        text = text + '00';
    return text;
}