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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>慕課網Wiki</title>
<style>
#imooc{
border:1px solid #ccc;
}
</style>
</head>
<body>
<canvas id="imooc">您的瀏覽器不支持 HTML5 canvas 標簽</canvas>
<script>
const canvas = document.getElementById('imooc');
canvas.width=300
canvas.height=300
const ctx = canvas.getContext('2d');
ctx.strokeStyle="#456795";
ctx.lineWidth=8;
ctx.arc(150, 150, 100, 0, 1*Math.PI, true); // 繪制半圓,傳遞了第六個參數為 true
ctx.stroke();
</script>
</body>
</html>
運行結果