Simple calculator (the effect is as shown in the picture)
The first solution: use Javascript html to complete the calculator, support -*/, and the result shows that the input input field is not allowed to be used (Consider using "span")
<html> <head> <title>简易计算器</title> <script language="javascript">//易错：不是"text/javascript" function doCal(){ //alert(document.getElementByName("value1").length);//易错：getElementByName,首字母大写，不是byName //alert(document.getElementByName("value1")[0].value);//易错：getElementByName，返回一个集合，应该用[0]表示需要获得第几个元素 var value1=parseInt(document.getElementById("value1").value);//易错：易错：getElementById首字母大写，不是byId var flag=document.getElementById("flag").value; var value2=parseInt(document.getElementById("value2").value);//易错：getElementBy返回是String类型，应该通过parseInt转换为Int类型 //alert(value1+","+flag+","+value2);//多打印东西出来，用于检验 var s=0; switch(flag){ case "+"://易错：语法，别忘记加冒号 s=value1+value2; break;//易错：语法，别忘记加break；跳出选择 case "-": s=value1-value2; break; case "*": s=value1*value2; break; case "/": s=value1/value2; } //使运算结果显示在浏览器中，注意=右侧为string类型 document.getElementById("span_result").innerHTML="<font size='16' color='red'>"+s+"</font>" } //alert(document.getElementByName(value1).value); </script> </head> <body> <h1>简易计算器</h1> <hr> <input type="text" name="value1" id="value1"> <select name="flag" id="flag">//注意select-option的用法 <option value="+">+</option> <option value="-">-</option> <option value="*">*</option> <option value="/">/</option> </select> <input type="text" name="value2" id="value2"> <!-- <button type="button" onclick="doCal()">点击这里</button> --> <input type="button" value="=" onclick="doCal()">//button的onclick事件 <!-- <input type="text" name="result" id="result"> --> <span id="span_result"></span>//通过span显示结果 </body></html>
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