var s = 'Hello World! Hello World! Hello World!';

var con = $('.container');

var index = 0;

var length = s.length;

var tId = null;

function start(){

  con.text('');

  tId=setInterval(function(){

    con.append(s.charAt(index));

    if(index++ === length){

    clearInterval(tId);

    index = 0;

    start()

    }

  },100);

}

start();