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来源：4-8 编程练习

2022一定转行成功

2021-04-28 07:57:51

相关代码：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body style="margin-top:50px;text-align: center;">
        <input type="text" id="num1">
        <select id="operate">
            <option value="+">+</option>
            <option value="-">-</option>
            <option value="*">×</option>
            <option value="/">÷</option>
        </select>
        <input type="text" id="num2">
        <input type="button" value="=" onclick="count()">
        <input type="text" id="result">    
    <script>

        function count(){
            var num1=document.querySelector("#num1").value,
                num2=document.querySelector("#num2").value,
                operate=document.querySelector("#operate").value,
                result=document.querySelector("#result");
            switch(operate){
                case "+":
                    result.value=+num1+ +num2;
                    break;
                case "-":
                    result.value=num1-num2;
                    break;
                case "*":
                    result.value=num1*num2;
                    break;
                case "/":
                    result.value=num1/num2;
                    break;
            }

        }
    </script>
</body>
</html>