圆周长面积的计算&＃xff0c;一个下拉列表框&＃xff0c;用于选择计算圆的周长或者是面积&＃xff0c;一个点击按钮进行计算。
也就是函数的调用
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<html lang&＃61;"en"><head><meta charset&＃61;"UTF-8"><meta http-equiv&＃61;"X-UA-Compatible" content&＃61;"IE&＃61;edge"><meta name&＃61;"viewport" content&＃61;"width&＃61;device-width, initial-scale&＃61;1.0"><title>对象title>
head><body>请输入圆的半径&＃xff1a;<input type&＃61;"text" name&＃61;"radius" id&＃61;"radius"><select name&＃61;"type" id&＃61;"type"><option value&＃61;"circle">周长option><option value&＃61;"area">面积option><option value&＃61;"volume">体积option>select><input type&＃61;"button" value&＃61;"计算" id&＃61;"btnCal"><script>function getCircle(r) {return 2 * Math.PI * Math.pow(r, 2);}function getArea(r) {return Math.PI * 2*r;}function getVolume(r) {return (4 / 3) * Math.PI * Math.pow(r, 2);}var x &＃61; document.getElementById("btnCal");x.onclick &＃61; function () {var r &＃61; parseFloat(document.getElementById("radius").value);var type &＃61; document.getElementById("type").value;var result;switch (type) {case &＃39;circle&＃39;: result &＃61; getCircle(r); break;case &＃39;area&＃39;: result &＃61; getArea(r); break;case &＃39;volume&＃39;: result &＃61; getVolume(r); break;default: result &＃61; 0;}alert("计算结果为" &＃43; result.toFixed(2));} script>
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