score 打印在canvas时当检测到碰撞时，score 会重复画，一直累加为什么会这样？求解答

var dataObj=function(){
  this.score=0;
this.ntrNum=0;
this.gameover=false;
}

dataObj.prototype.draw=function(){
  // var w=can1.width;
  // var h=can1.height;

  ctx1.fillStyle = "white";

  // ctx1.fillText=("score"+this.score,canWidth*0.5,canHeight/12);
    ctx1.fillText("score  "+this.score,canWidth*.5,canHeight-20);
    ctx1.fillText("ntrNUm  "+this.ntrNum,canWidth*.5,canHeight-50);

console.log(this.score)

}

  dataObj.prototype.addScore=function(){
    // if(this.ntrNum>0){
      this.score+=this.ntrNum*10;
    // }
    this.ntrNum=0;

  }