将 JavaScript 代码分解为函数

Question

新手学生编码员，

在这里，我正在开发一个程序，该程序可以提醒程序，一旦您输入您提供的金额，它就会计算小费和税收以获得用户拥有的总金额。我记下了基本代码并将其分成函数，但是当我输入一个数字时，它显示为身份不明。

这是我的代码：

const TAXRATE=.095
const TIPRATE=.2

function foodCharge (foodCharge) {
  return parseFloat(prompt("please enter the amount"));
}
foodCharge ();

function taxAmount (foodCharge,TAXRATE) {
  return parseFloat(foodCharge*TAXRATE);
}

taxAmount();


function subAmount (foodCharge,taxAmount) {
  return parseFloat(foodCharge+taxAmount);
}
subAmount ();

function tipAmount (TAXRATE,subAmount) {
  return parseFloat (TAXRATE*subAmount);
}
tipAmount ();


function grandTotal (foodCharge, taxAmount, tipAmount) {
  return grandTotal=parseFloat(foodCharge+taxAmount+tipAmount)
}
grandTotal ();

function finalCost(foodCharge,taxAmount, tipAmount, grandTotal ) { 
   alert ("Meal cost: "+ foodCharge + " \nTax: " + taxAmount + "  \nTip: " + 
    tipAmount +" \nGrand total: " + grandTotal);
}
finalCost();

Answer 1

您可以调整在finalCost内调用的函数。注意，parseFloat() 仅在 foodCharge 函数

处是必需的

const TAXRATE = .095
const TIPRATE = .2

function foodCharge() {
  return parseFloat(prompt("please enter the amount"));
}

function taxAmount(charge, tax) {
  return charge * tax;
}

function subAmount(charge, tax) {
  return charge + tax;
}

function tipAmount(tip, sub) {
  return tip * sub;
}

function grandTotal(charge, tax, tip) {
  return charge + tax + tip;
}

function finalCost() {

  let _foodCharge = foodCharge();
  let _taxAmount = taxAmount(_foodCharge, TAXRATE);
  let _subAmount = subAmount(_foodCharge, _taxAmount);
  let _tipAmount = tipAmount(TIPRATE, _subAmount);
  let _grandTotal = grandTotal(_foodCharge, _taxAmount, _tipAmount);

  alert("Meal cost: " + _foodCharge + " \nTax: " + _taxAmount + "  \nTip: " +
    _tipAmount + " \nGrand total: " + _grandTotal);
}

finalCost();

Answer 2

只有在从字符串中解析浮点数时才需要parseFloat函数。您不需要解析常规数学运算的结果（如果两个数字都不是字符串）。当您将函数作为参数传递给 alert() 时，您必须用方括号 () 传递它，否则你将引用传递给一个函数。

如果我正确理解了你的问题，这是你的程序：

const TAXRATE=0.095
const TIPRATE=0.2


function foodCharge (foodCharge) {
  return parseFloat(prompt("please enter the amount"));
}
var charge = foodCharge ();


function taxAmount (charge, rate) {
  return charge*rate;
}
var tax = taxAmount(charge, TAXRATE);


function subAmount (charge,tax) {
  return charge+tax;
}
var amount = subAmount (charge,tax);


function tipAmount (rate,amount) {
  return rate*amount;
}
var tip = tipAmount(TAXRATE,amount);


function grandTotal () {
  return charge+tax+tip;
}


function finalCost() {
  alert ("Meal cost: "+ charge + " \nTax: " + tax + "  \nTip: " + amount +" \nGrand total: " + grandTotal());
}
finalCost();

将 JavaScript 代码分解为函数

Breaking down a JavaScript code into functions

javascript

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