PS#1: HTML/JS/CSS to run locally

HTML

<h5 id="title">Type something in the input box and click 'Change'</h5>
<input type="text" id="myTextField"/>
<input type="submit" id="myBtn" value="Change"/>

CSS

#title{
    color: #555;
    padding: 1em;
    border: 1px solid #111;
}

JavaScript

document.getElementById("myBtn").onclick = function(){
    
   var myNewTitle = document.getElementById('myTextField').value;
   if( myNewTitle.length==0 ){
       alert('Write Some real Text hi please.');
   return;
   }
   
   var title = document.getElementById('title');
   title.innerHTML = myNewTitle;
    
}