1. var RecentCounter = function() {
    2.   this.queue = []
    3. };
    5. /** 
    6.  * @param {number} t
    7.  * @return {number}
    8.  */
    9. RecentCounter.prototype.ping = function(t) {
    10.   this.queue.push(t)
    12.   while(this.queue[0] < t - 3000) {
    13.     this.queue.shift()
    14.   }
    16.   return this.queue.length
    17. };
    19. /**
    20.  * Your RecentCounter object will be instantiated and called as such:
    21.  * var obj = new RecentCounter()
    22.  * var param_1 = obj.ping(t)
    23.  */