Question

我最近启动了JavaScript，并且正在开发一个简单的税计算器，我唯一的问题是输出返回undefined而不是期望值。例如，当我输入320000时，所得税应为14000，但它返回的是undefined。我尝试将calculation设置为0，但是并不能解决问题。是什么使我的函数不返回期望值？我看过我的大学给出的示例程序，这些程序在条件中使用变量，它们可以正常工作，但我的不是。

function calculateTax()
{
    var taxableIncome, calculation;
    taxableIncome = document.getElementById("t").value * 1;

    if (taxableIncome > 250000) {
        calculation = 0;
    }
    else if (taxableIncome > 250000 && taxableIncome < 40000) {
        calculation = (taxableIncome - 250000) * 0.20; 
    }
    else if (taxableIncome > 400000 && taxableIncome < 800000) {
        calculation = ((taxableIncome - 400000) * 0.25) + 30000;
    }
    else if (taxableIncome > 800000 && taxableIncome < 2000000) {
        calculation = ((taxableIncome - 800000) * 0.30) + 130000;
    }
    else if (taxableIncome > 2000000 && taxableIncome < 8000000) {
        calculation = ((taxableIncome - 2000000) * 0.32);
    }
    else if (taxableIncome > 8000000) {
        calculation = ((taxableIncome - 8000000) * 0.35) + 2410000;
    }

    document.getElementById("inputTax").innerHTML = "The taxable income is:" +taxableIncome;
    document.getElementById("incomeTax").innerHTML = "The income tax is:" +calculation;
}

<h1>Income Tax Calculator</h1>

<p>
<label for = "t">Taxable Income</label> 
<input type = "number" id="t" name="t">
<button onclick = "calculateTax()"> Calculate Tax </button>
</p>

<h2 id="inputTax"></h2>
<h2 id="incomeTax"></h2>

Answer 1

对于值320000，对于taxableIncome > 250000，条件始终为 true ，并返回0。此外，值40000（在第二种情况下使用）和400000（在第三种情况下使用）之间不匹配。

您应将以下前两个条件更改为：

if (taxableIncome < 250000) {

else if (taxableIncome > 250000 && taxableIncome < 400000) {

请注意：：您不需要检查最终条件（taxableIncome > 8000000），只需else就可以。

演示：

function calculateTax()
{
    var taxableIncome, calculation;
    taxableIncome = document.getElementById("t").value * 1;

    if (taxableIncome < 250000) {
        calculation = 0;
    }
    else if (taxableIncome > 250000 && taxableIncome < 400000) {
        calculation = (taxableIncome - 250000) * 0.20; 
    }
    else if (taxableIncome > 400000 && taxableIncome < 800000) {
        calculation = ((taxableIncome - 400000) * 0.25) + 30000;
    }
    else if (taxableIncome > 800000 && taxableIncome < 2000000) {
        calculation = ((taxableIncome - 800000) * 0.30) + 130000;
    }
    else if (taxableIncome > 2000000 && taxableIncome < 8000000) {
        calculation = ((taxableIncome - 2000000) * 0.32);
    }
    else{
        calculation = ((taxableIncome - 8000000) * 0.35) + 2410000;
    }

    document.getElementById("inputTax").innerHTML = "The taxable income is:" +taxableIncome;
    document.getElementById("incomeTax").innerHTML = "The income tax is:" +calculation;
}

<h1>Income Tax Calculator</h1>

<p>
<label for = "t">Taxable Income</label> 
<input type = "number" id="t" name="t">
<button onclick = "calculateTax()"> Calculate Tax </button>
</p>

<h2 id="inputTax"></h2>
<h2 id="incomeTax"></h2>

JavaScript输出返回未定义

1 个答案: