W3School TIY
编辑您的代码：
<!DOCTYPE html> <html> <body> <h3>演示如何访问 MAP 元素</h3> <img src="../i/eg_planets.jpg" border="0" usemap="#myMap" alt="Planets" /> <map name="myMap" id="myMap"> <area shape="circle" coords="180,139,14" href ="../example/html/venus.html" target ="_blank" alt="Venus" /> <area shape="circle" coords="129,161,10" href ="../example/html/mercur.html" target ="_blank" alt="Mercury" /> <area shape="rect" coords="0,0,110,260" href ="../example/html/sun.html" target ="_blank" alt="Sun" /> </map> <p>点击按钮来获得图像映射中 area 元素的数目。</p> <p id="demo"></p> <button onclick="myFunction()">试一下</button> <script> function myFunction() { var x = document.getElementById("myMap").areas.length; document.getElementById("demo").innerHTML = x; } </script> </body> </html>
查看结果: