JS 裏Sleep延時執行，可多個順序延時

        function sleep(delay){
          return function(){
            return new Promise(function(resolve, reject){
              setTimeout(resolve, delay);
            });
          }
        }

        //延時執行
        var promise = new Promise(function(resolve){
          console.log('1 do something');
          resolve();
        }).then(sleep(2000)).then(function(){
          console.log('2 after sleep 2000');
        }).then(sleep(2000)).then(function(){
          console.log('3 after sleep 2000');
        }).then(sleep(2000)).then(function(){
          console.log('4 after sleep 2000');
        })