(function(){

    var days = ['Sun','Mon','Tue','Wed','Thu','Fri','Sat']

    var today = new Date()

    var msg = "Today is" + days[today.getDay()] + ',' + today.getDate()

    console.log(msg)

})();   // Today isThu,29

// 即时函数的参数

(function(who,when){

    console.log(' i met ' + who + ' on ' + when)

})("cynthai",new Date());  //i met cynthai on Thu Oct 29 2015 18:03:09 GMT+0800 (中国标准时间)