window.onload=function(){
????var?chess=document.getElementById('chess');
????var?context=chess.getContext('2d');

????context.strokeStyle="#BFBFBF";

????for?(var?i=0;i<15;i++){
????????context.moveTo(15?+?i?*?30,15);
????????context.lineTo(15?+?i?*?30,435);
????????context.stroke();
????????context.moveTo(15,15?+?i?*?30);
????????context.lineTo(435,15?+?i?*?30);
????????context.stroke();?
????????
????}
}

為什么我的棋盤是這樣的，寬和高都是450px呀！