JavaScript 实例：计算器

来源：互联网发布：java 注解用处编辑：程序博客网时间：2024/06/06 15:48
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><HTML> <HEAD>  <TITLE> 计算器 </TITLE>  <META name="Generator" content="EditPlus">  <META name="Author" content="">  <META name="Keywords" content="">  <META name="Description" content="">  <style type="text/css">  </style>  <script type="text/javascript">function calcu(){var num1=document.getElementById("text1").value;var num2=document.getElementById("text2").value;var num3=document.getElementById("text3");if(num1=="" || num1==""){alert("请先输入数据！");}//alert(num2);num1=parseInt(num1);  //从网页获取的value都是字符串，要先转换成数字再进行计算num2=parseInt(num2);var symbol=document.getElementById("symbol").value;var result;switch (symbol){case "+":  result=num1+num2;  break;case "-":  result=num1-num2;  break;case "x":  result=num1*num2;  break;case "/":  result=num1/num2;  break;default:  alert("请选择运算符号！");}if (isNaN(result)){result="0"}num3.value=(result);}  </script> </HEAD> <BODY>  <input type="text" id="text1" />  <select id="symbol">   <!--下拉列表框--><option value="+">+</option><option value="-">-</option><option value="x">x</option><option value="/">/</option>  </select>  <input type="text" id="text2" />  =  <input type="text" id="text3" />  <input type="button" id="button1" value="计算" onclick="calcu()" /> </BODY></HTML>
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