最後一次彈出執行之後，把定時器清除不就行了…

        function first(){
            alert('第一次');
            setTimeout(second,20000);
        }
        function second(){
            alert('第二次');
            setTimeout(third,40000);
        }
        function third(){
            alert('第三次')
        }
        setTimeout(first,10000);

這樣不知道能不能行

        var firstShow=1000;
        var secondShow=5000;
        var threeShow=10000;
        var n=0;
        setTimeout(openMpM,1000);
        function openMpM() {
            $("#swtCenter2").fadeIn(1000);
            $("#swtCenter2").fadeOut(1000);
            n++;
            switch (n){
                case 1:
                setTimeout(openMpM,secondShow);
                    break;
                case 2:
                setTimeout(openMpM,threeShow);
                    break;    
            }
        }

顯示隱藏條件 你自己加

<p id="box"></p>
    <button id="btn">hide</button>
    <script>
        var times = [2000, 4000, 6000];
        function State(times) {
            var self = this;
            this.times = times
            this.oBox = document.getElementById('box');
            this.btn = document.getElementById('btn');
            this.i = 0;

            this.btn.onclick = function() {
                self.change()
            }
        }
        State.prototype.show = function() {
            var self = this;
            setTimeout(function() {
                self.oBox.style.display = "block";
            }, this.times[this.i++])
        }
        State.prototype.change = function(time) {
            if(this.i == this.times.length) {
                alert('没有数据了');
                return;
            }
            this.oBox.style.display = 'none';
            this.time = time
            this.show();
        }
        var s = new State(times);
        s.show();
    </script>

你參考下這個，關閉的時候是手動點擊關閉的

簡單實現了一下，不知道有沒有滿足你的需求

var timer,num=4;
$('关闭').on('click',function(){
  $("#swtCenter2").fadeOut();
  clearInterval(timer);
  alertTime();
});

function alertTime(){
  num--;
  if(num<=0){
   clearInterval(timer);
   return false;
  }
  timer=setInterval(function(){
    $("#swtCenter2").fadeIn();
  },10000);
}
alertTime();

搞錯時間了，稍微改了一下，應該就是這樣

var timer,num=-1;
$('关闭').on('click',function(){
  $("#swtCenter2").fadeOut(0);
  clearInterval(timer);
  alertTime();
});

function alertTime(){
  num++;
  var idx=num;
  idx=!idx?0.5:idx;
  if(num>2){
   clearInterval(timer);
   return false;
  }
  timer=setInterval(function(){
    $("#swtCenter2").fadeIn(0);
  },10000*2*idx);
}
alertTime();