<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<style>
#flag{
width: 600px;
height: 400px;
background-color: #DE2910;
}
</style>
</head>
<body align="center">
<canvas id="flag" width=600 height="400"></canvas>
<script>
var flag=document.getElementById("flag");
var ctx=flag.getContext('2d'); function drawStar(x,y,r,deg){//xy中心坐标,r半径,deg旋转角度
ctx.beginPath();
ctx.translate(x,y);
ctx.rotate(deg*Math.PI/180);
var dit = Math.PI * 4 / 5;
var sin = Math.sin(0) * r;
var cos = Math.cos(0) * r;
ctx.moveTo(cos, sin);
for (var i = 0; i < 5; i++) {
var tempDit = dit * i;
sin = Math.sin(tempDit) * r;
cos = Math.cos(tempDit) * r;
ctx.lineTo(cos, sin);
}
ctx.closePath();
ctx.fillStyle = "#ffde00";
ctx.fill();
ctx.rotate(-deg*Math.PI/180);
ctx.translate(-x,-y);
} drawStar(100,100,60,-18);
drawStar(200,40,20,0);
drawStar(240,80,20,27);
drawStar(240,140,20,-18);
drawStar(200,180,20,0);
</script>
</body>
</html>