code: function() {
          // Put all the particles back
          for (var i = 0; i < this._particles.length; i++) {
              var p = this._particles[i];
              p.emitter.kill(p);
          }
          this._particles.length = 0;
          this._elapsedTime = 0;
          this._emitting = true;
      }
docs: Reset the particle system.