<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(動態時間間隔) 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>錯誤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