递归功能返回未定义

Question

我的功能可以计算税收。

function taxes(tax, taxWage) 
{
    var minWage = firstTier; //defined as a global variable
    if (taxWage > minWage) 
    {
        //calculates tax recursively calling two other functions difference() and taxStep() 
        tax = tax + difference(taxWage) * taxStep(taxWage);
        var newSalary = taxWage - difference(taxWage);
        taxes(tax, newSalary); 
    }
    else 
    {
        returnTax = tax + taxWage * taxStep(taxWage);
        return returnTax;
    }
} 

我看不出为什么它不会停止递归。

Answer 1

在您的功能的此部门中：

if (taxWage > minWage) {
    // calculates tax recursively calling two other functions difference() and taxStep() 
    tax = tax + difference(taxWage) * taxStep(taxWage);
    var newSalary = taxWage - difference(taxWage);
    taxes(tax, newSalary); 
}

您没有从功能或设置return tax中返回值。当您不返回任何内容时，返回值为undefined。

也许，您想要这个：

if (taxWage > minWage) {
    // calculates tax recursively calling two other functions difference() and taxStep() 
    tax = tax + difference(taxWage) * taxStep(taxWage);
    var newSalary = taxWage - difference(taxWage);
    return taxes(tax, newSalary); 
}

Answer 2

递归中有一个错误：

taxes(tax, newSalary);

如果在true中评估中的条件时，您不会返回任何内容。您需要将其更改为：

return taxes(tax, newSalary);

您在else> else中具有必要的返回语句。

Answer 3

例如税收（税，新闻）;返回100;

taxes(tax, newSalary); // undefined

您期望看到100，因为您递归地称呼税收（税，新闻），但实际上您获得了值（100），您需要返回此值。

return taxes(tax, newSalary); // 100
// simply it's the same as
// return 100
// because taxes(tax, newSalary) returned 100

返回100后，您将获得此值。