案例：javascript案例     状态：可编辑再运行    进入竖版
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<!DOCTYPE html>
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<html>
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<body>
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​
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<h3>演示如何访问 MAP 元素</h3>
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<img src="/img/eg_planets.jpg" border="0" usemap="#myMap" alt="Planets" />
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<map name="myMap" id="myMap">
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<area
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shape="circle"
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coords="180,139,14"
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href ="/example/html/venus.html"
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target ="_blank"
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alt="Venus" />
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<area
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shape="circle"
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coords="129,161,10"
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href ="/example/html/mercur.html"
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target ="_blank"
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alt="Mercury" />
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<area
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shape="rect"
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coords="0,0,110,260"
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href ="/example/html/sun.html"
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target ="_blank"
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alt="Sun" />
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​
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</map>
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<p>点击按钮来获得图像映射中 area 元素的数目。</p>
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<p id="demo"></p>
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<button onclick="myFunction()">试一下</button>
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<script>
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function myFunction()
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{
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var x = document.getElementById("myMap").areas.length;
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document.getElementById("demo").innerHTML = x;
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}
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</script>
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​
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</body>