果实不显示，怎么办？

var fruitObj=function()
{
 this.alive=[];//bool
 this.x=[];
 this.y=[];
 this.l=[];
 this.orange=new Image();
 this.blue=new Image();
}
fruitObj.prototype.num=30;
fruitObj.prototype.init=function()
{
 for(var i=0;i<this.num;i++)
 {
  this.alive[i]=true;
  this.x[i]=0;
     this.y[i]=0;
  this.born(i);
 }
 this.orange.src="./src/fruit.png";
 this.blue.src="./src/blue.png";
}
fruitObj.prototype.draw=function()
{
 for(var i=0;i<this.num;i++)
 {
  //draw
  //find an ane,grow,fly up;
  if(this.l[i] <= 14)
  {
   this.l[i] += 0.01*deltaTime;
  }
  ctx2.drawImage(this.orange,this.x[i] - this.l[i]*0.5,this.y[i] -  this.l[i]*0.5,this.l[i],this.l[i]);
 }
}
fruitObj.prototype.born=function(i)
{
 var aneID=Math.floor(Math.random()*ane.num);
 this.x[i]=ane.x[aneID];
 this.y[i]=canHeight - ane.len[aneID];
 this.l[i]=0;
}