javascript - 调用函数失败

Question

我正在编写一个简单的 javscript 程序，在提交按钮上我调用 find_amount() 函数，但是我不断收到“ReferenceError:find_amount 未定义”。我做错了什么？我已经尝试了几种方法，但无法让它发挥作用，尽管我之前多次尝试过这种方法并且效果很好。

<form id="myForm">

    <strong>Loan: <input type="text" name="loan" id="loan" value="" size="10"></strong>&nbsp;&nbsp;
    <select id="duration" onclick="onSelectChange(this)" style="width: 85px">
        <option value=" "></option>
        <option value="three">3 years</option>
        <option value="five">5 years</option>
        <option value="six">6 years</option>
    </select> &nbsp;&nbsp;
    <strong>Interest: <input type="text" name="interest" id="interest" value="" size="10"></strong>
    <button type="button" onclick="find_amount();">Submit</button></br></br>
    <strong>Total amount to be returned: <input type="text" name="return" id="return" value="" size="10"></strong></br></br>
    <strong>Installments</strong>
    <select id="installments" onclick="onSelectChange(this)" style="width: 85px">
        <option value=" "></option>
        <option value="year">per year</option>
        <option value="month">per month</option>
        <option value="week">per week</option>
        <option value="day">per day</option>
    </select> &nbsp;&nbsp;<strong>:</strong>
    <span id="final"></span>
</form>

JavaScript:

function onSelectChange(combo) {

    switch (combo.value) {
        case "three":
            {
                document.getElementById("interest").value = " 3% ";
                break;
            }
        case "five":
            {
                document.getElementById("interest").value = " 5% ";
                break;
            }
        case "six":
            {
                document.getElementById("interest").value = " 6% ";
                break;
            }

        case " ":
            {
                document.getElementById("interest").value = " ";
                break;
            }

    }
    function find_amount() {
        var total;
        var inter;
        var lo;

        lo = document.getElementById("loan").value;
        inter = document.getElementById("interest").value;
        total = (lo * inter) / 100;
        alert(total);
        //document.getElementById("return").value = total;
    }
}

Answer 1

您的 find_amount() 函数是在您的 onSelectChange() 函数中定义的，该函数之外的任何人都看不到它。尝试将这两个函数分开，如下所示:

JS

function onSelectChange(combo) {

    switch(combo.value) {
        case "three" : 
        {   
            document.getElementById("interest").value = " 3% ";
            break;
        }
        case "five" : 
        {   
            document.getElementById("interest").value = " 5% ";
            break;
        }
        case "six" : 
        {   
            document.getElementById("interest").value = " 6% ";
            break;
        }

        case " " : 
        {   
            document.getElementById("interest").value = " ";
            break;
        }

    }
}
function find_amount(){
    var total;
    var inter;
    var lo;

    lo = document.getElementById("loan").value;
    inter = document.getElementById("interest").value;
    total = (lo * inter)/100;
    alert(total);
    //document.getElementById("return").value = total;
}