Edit in JSFiddle

var app = document.getElementById('app');

var typewriter = new Typewriter(app, {
    loop: true
});

typewriter.typeString('Hello World!')
    .pauseFor(2500)
    .deleteAll()
    .typeString('Strings can be removed')
    .pauseFor(2500)
    .deleteChars(7)
    .typeString('altered!')
    .start();
<div id="app"></div>

              
            
          
            
              

External resources loaded into this fiddle: