document.addEventListener('DOMContentLoaded',function(){
document.oncontextmenu=function(){
return false;
};
let canvas=document.getElementById('canvas');
canvas.width=canvas.clientWidth;
canvas.width=canvas.clientHeight;
//代码区↓↓↓↓↓↓↓↓↓↓
//1.每次右击，绘制一个随机颜色的50x50大小对的方块在位置上。
//2,可以拖动方块改变其位置;
//代码区↑↑↑↑↑↑↑↑↑↑
});
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
</head>
<body>
<canvas id="canvas"></canvas>
</body>
</html>
body{
margin:0;
position:absolute;
width:100%;
height:100%;
overflow:hidden;
}
canvas{
width:100%;
height:100%;
background:#e8e8e8;
}