Question

我正在开发一个程序来输入学生的标记并对其进行添加操作。我的代码是：

<html>
    <head>
        <script type="text/javascript">
            function fstudent()
            {
                var m1 =eval(document.getElementById("txtmarks1")).value;
                var m2 =eval(document.getElementById("txtmarks2")).value;
                var m3 =eval(document.getElementById("txtmarks3")).value;
                var total =m1+m2+m3;
                alert("total marks is"+total);
            }
        </script>
    </head>
    <body>
        <form name="STUDENT">
            <table>
                <tr>
                    <td>Enter StudentNo:</td>
                    <td><input type="number" id="numSno"></td>
                </tr>
                <tr>
                    <td>Enter StudentName:</td>
                    <td><input type="text" id="txtSname"></td>
                </tr>
                <tr>
                    <td>Enter Marks1:</td>
                    <td><input type="text" id="txtmarks1"></td>
                </tr>
                <tr>
                    <td>Enter Marks2:</td>
                    <td><input type="text" id="txtmarks2"></td>
                </tr>
                <tr>
                    <td>Enter Marks3:</td>
                    <td><input type="text" id="txtmarks3"></td>
                </tr>
                <tr>
                    <td></td>
                    <td><input type="submit" value="Calculate Total Marks" onclick="fstudent()"></td>
                </tr>
            </table>
        </form>
    </body>
</html>

当我对它执行加法运算时，它返回一个字符串值，但是当我对它执行乘法运算时，它返回一个整数值。我尝试使用parseInt方法将string转换为int，但它也仅提供字符串值。

Answer 1

如果只能输入整数：

var m1 = parseInt(document.getElementById("txtmarks1").value, 10);

如果允许浮动：

var m1 = parseFloat(document.getElementById("txtmarks1").value);

Answer 2

<html>
<head>
    <script type="text/javascript">
        function fstudent() {
            var m1 = document.getElementById("txtmarks1").value;
            var m2 = document.getElementById("txtmarks2").value;
            var m3 = document.getElementById("txtmarks3").value;
            var total = parseInt(m1) + parseInt(m2) + parseInt(m3);
            alert("total marks is" + total);
        }
    </script>
</head>
<body>
    <form name="STUDENT">
    <table>
        <tr>
            <td>
                Enter StudentNo:
            </td>
            <td>
                <input type="number" id="numSno">
            </td>
        </tr>
        <tr>
            <td>
                Enter StudentName:
            </td>
            <td>
                <input type="text" id="txtSname">
            </td>
        </tr>
        <tr>
            <td>
                Enter Marks1:
            </td>
            <td>
                <input type="text" id="txtmarks1">
            </td>
        </tr>
        <tr>
            <td>
                Enter Marks2:
            </td>
            <td>
                <input type="text" id="txtmarks2">
            </td>
        </tr>
        <tr>
            <td>
                Enter Marks3:
            </td>
            <td>
                <input type="text" id="txtmarks3">
            </td>
        </tr>
        <tr>
            <td>
            </td>
            <td>
                <input type="submit" value="Calculate Total Marks" onclick="fstudent()">
            </td>
        </tr>
    </table>
    </form>
</body>
</html>

如何将字符串转换为整数？

2 个答案: