js实现打字机效果

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();

参考：http://www.cnblogs.com/dolphinX/p/4087817.html