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<meta charset="utf-8">5
<title>菜鸟教程(runoob.com)</title>6
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<body>8
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<canvas id="myCanvas" width="200" height="200" style="border:1px solid">10
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<script>15
var c = document.getElementById("myCanvas");16
var ctx = c.getContext("2d");17
ctx.fillStyle = "#92B901";18
ctx.fillRect(50, 50, 100, 100);19
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function clearCanvas() {21
c.height = 300;22
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<button onclick="clearCanvas()">清空画布</button>26
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</body>28
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