Question

<head>
    <title>Javascript Test</title>
</head>

<body>
<script>
        function calc_form() {
            discPerc = document.forms["calc"].elements["disc_perc"].value;
            totDays = document.forms["calc"].elements["tot_days"].value;
            discPer = document.forms["calc"].elements["disc_per"].value;
            discDays = document.forms["calc"].elements["disc_days"].value;
            discCalc = Math.round([(discPerc/100)/((100-discPerc)/100)]*(totDays/(discPer-discDays)));
            document.forms["calc"].elements["result"].value = discCalc*100 + "%";
            document.getElementById("result1").innerHTML = discCalc*100 + "%";
            //return Math.round(discCalc);
        }
    </script>
<form name = "calc">
    Discount Percentage:
    <br>
    <input type = "text" name="disc_perc">
    <br>
    Enter Total Days in a year:
    <br>
    <input type="text" name="tot_days">
    <br>
    Enter Discount Days:
    <br>
    <input type="text" name="disc_days">
    <br>
    Enter Discount Period
    <br>
    <input type="text" name="disc_per">
    <input type="button" value="Calculate" onclick = "calc_form()">
    <br>   <br>
    Cost of forgoing discount:
    <br>
    <input type="text" id="result">
</form>
<p id="result1"></p>

</body>

以上代码产生意外结果。当然，它有一个错误，但我无法理解。当我在Math.round函数中包含discCalc变量时，输出完全不同于我没有。

请有人解释这种差异。

谢谢。

Answer 1

我只是通过使用variable.toFixed（2）而不是使用Math.round（）函数来解决问题。所以代码是：

<script>
        function calc_form() {
            discPerc = document.forms["calc"].elements["disc_perc"].value;
            totDays = document.forms["calc"].elements["tot_days"].value;
            discPer = document.forms["calc"].elements["disc_per"].value;
            discDays = document.forms["calc"].elements["disc_days"].value;
            //discCalc = Math.round([(discPerc/100)/((100-discPerc)/100)]*(totDays/(discPer-discDays)));
            discCalc = [(discPerc)/((100-discPerc))]*(totDays/(discPer-discDays));
            discCalc_2 = discCalc*100;
            document.forms["calc"].elements["result"].value = discCalc_2.toFixed(2) + "%";
            document.getElementById("result1").innerHTML = discCalc_2.toFixed(2) + "%";
            //return Math.round(discCalc);
        }
    </script>
<form name = "calc">
    Discount Percentage:
    <br>
    <input type = "text" name="disc_perc">
    <br>
    Enter Total Days in a year:
    <br>
    <input type="text" name="tot_days">
    <br>
    Enter Discount Days:
    <br>
    <input type="text" name="disc_days">
    <br>
    Enter Discount Period
    <br>
    <input type="text" name="disc_per">
    <input type="button" value="Calculate" onclick = "calc_form()">
    <br>   <br>
    Cost of forgoing discount:
    <br>
    <input type="text" id="result">
</form>
<p id="result1"></p>

Javascript计算产生意外结果

1 个答案: