预期效果是实现鼠标点击是画一个三角形。，chrome可以运行。
代码如下
<!DOCTYPE html>
<html lang="zh">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>CANVAS测试代码</title>
</head>
<body>
<canvas id="canvas" width="300" height="300"></canvas>
<script type="text/javascript" charset="utf-8">
var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
canvas.onmousedown=function (event) {
var x=event.x;
var y=event.y;
var r= Math.random()*10+5;
ctx.beginPath();
ctx.moveTo(x, y);
ctx.lineTo(x, y+r);
ctx.lineTo(x+r, y+r);
ctx.lineTo(x, y);
ctx.strokeStyle = "red";
ctx.stroke();
};
</script>
</body>
</html>
![[웹 프런트엔드] Node.js 빠른 시작](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
firefox有
event.clientX,event.pageX,event.layerX等鼠标相关坐标的属性，就是没有event.x