求大神帮看一下为什么不出现果实呢

//action.js
var can1,
    can2;
var ctx1,
	ctx2;
var lastTime,
	deltaTime;
var canWidth,
	canHeight;
var bgPic=new Image();	
var ane,
	fruit;
var mom;
var mx,
	my;

document.body.onload=game;
function game(){
	init();
	lastTime=Date.now();
	deltaTime=0;
	gameloop();
}

function init(){
	can1=document.getElementById("canvas1");
	ctx1=can1.getContext('2d');
	can2=document.getElementById("canvas2");
	ctx2=can2.getContext('2d');

	can1.addEventListener('mousemove',onMouseMove,false);

	bgPic.src="./img/background.jpg";

	canWidth=can1.width;
	canHeight=can1.height;

	ane=new aneObj();
	ane.init();

	fruit=new fruitObj();
	fruit.init();

	mom=new momObj();
	mom.init();

	mx=canWidth*0.5;
	my=canHeight*0.5;
}

function gameloop(){
	window.requestAnimFrame(gameloop);
	var now=Date.now();
	deltaTime=deltaTime<50?now-lastTime:50;//解决暂停网页，球无限变大bug
	lastTime=now;
	drawBackground();
	ane.draw();
	fruitMonitor();
	fruit.draw();

	ctx1.clearRect(0,0,canWidth,canHeight);
	mom.draw();
	momFruitCollision();

}

function onMouseMove(e){ //获取鼠标移动位置
	if(e.offsetX||e.layerX){
		mx=e.offsetX==undefined? e.layerX:e.offsetX;
		my=e.offsetY==undefined? e.layerY:e.offsetY;
	}
}

//fruit.js
var fruitObj=function(){
	this.isalive=[];
	this.x=[];
	this.y=[];
	this.l=[];
	this.spd=[];
	this.fruitType=[];
	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.isalive[i]=false;
		this.x[i]=0;
		this.y[i]=0;
		this.spd[i]=Math.random()*0.017+0.003;
		this.born(i);
		this.fruitType[i]="";
		
	}
	this.orange.src="./img/fruit.png";
	this.blue.src="./img/blue.png";
}
fruitObj.prototype.draw=function(){
	for(var i=0;i<this.num;i++){

		var pic;
		if(this.isalive[i]){
			if(this.fruitType[i]=="blue"){
				pic=this.blue;
			}else{
				pic=this.orange;
			}
			if(this.l[i]<=14){
				this.l[i]+=this.spd[i]*deltaTime;
			}
			else{
				this.y[i]-=this.spd[i]*6*deltaTime;
			}
			ctx2.drawImage(pic,this.x[i]-this.l[i]*0.5,this.y[i]-this.l[i]*0.5,this.l[i],this.l[i]);
			if(this.y[i]<10){
				this.isalive[i]=false;
			}
		}

	}
	
}
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;
	this.isalive=true;
	var ran=Math.random();
	if(ran<0.3){
		this.fruitType[i]="blue";
	}else{
		this.fruitType[i]="orange";
	}
	
}
fruitObj.prototype.dead=function(i){
	this.isalive[i]=false;
}



function fruitMonitor(){
	var num=0;
	for(var i=0;i<fruit.num;i++){
		if(fruit.isalive[i]) num++;
	}
	if(num<15){
		sendFruit();
		return;
	}
}

function sendFruit(){
	for(var i=0;i<fruit.num;i++){
		if(!fruit.isalive[i]){
			fruit.born(i);
			return;
		}
	}
}