这是什么错误？？

Question

<script>

var can1;

var can2;

var ctx1;

var ctx2;

var lastTime;

var deltaTime;

document.body.onload=game;

function game(){

init();

gameloop();

}

function init(){

    can1=document.getElementById("canvas1");//fishes,dust,UI,circle

    ctx1=can1.getContext();

    can2=document.getElementById("canvas2");//background,ane,fruits

    ctx2=can2.getContext();

    

}

function gameloop(){

requestAnimFrame(gameloop);//frame per second(动态时间间隔)

var now=date.now();

deltaTime=now-lastTime;

lastTime=now;

console.log(lastTime)

}

<script>

body>

<div class="all_bg">

<div id="allcanvas">

<canvas id="canvas1" width="800px" height="600px">

   </canvas>

   <canvas id="canvas2" width="800px" height="600px">

   

   </canvas>

</div>

</div>

<script type="text/javascript" src="js/main.js"></script>

<script type="text/javascript" src="js/commonFunctions.js"></script>

</body>

错误

Uncaught TypeError: Failed to execute 'getContext' on 'HTMLCanvasElement': 1 argument required, but only 0 present.     at init (VM82 main.js:16)     at game (VM82 main.js:11) init @ VM82 main.js:16 game @ VM82 main.js:11

Answer 1

getContext方法需要接收参数：2d

Answer 2

getContext方法没定义