如何在JavaScript中插入字典值作為引數？-有解無憂

我正在輸出一個陣列，該陣列將根據loanAmount,interest和loanTermYears為字典回傳貸款欠款instance1。字典列印成功。但是，calculatedLoanAmount回傳 NaN。函式 calculateAmount 未正確讀取鍵值對。如何正確插入這些鍵值對作為引數，以便函式可以回傳欠款總額？

var info = []
var instance1 = new Object();

var instance1 = {
    Id: 0,
    customerName: "Khawaja Sardar",
    phoneNumber: "745-544-7777",
    address: "New York, NY",
    loanAmount: 5000,
    interest: 6.0,
    loanTermYears: 5,
    loanType: "APR",
    description: "Loan domain for instance1",
    calculatedLoanAmount: calculateAmount(instance1.loanAmount, instance1.interest, instance1.loanTermYears)

    }

function calculateAmount(loanAmount, interest, loanTermYears) {
    var totalMonth = loanTermYears * 12;
    var montlyInterest = interest / 100 / 12;
    var temp = Math.pow(1   montlyInterest, totalMonth);
    var monthlyPayment = loanAmount * montlyInterest * temp / (temp - 1);
    var sum =  monthlyPayment * totalMonth
    var totalAmount = sum

    return totalAmount
    
}

info.push(instance1)

console.log(info)

uj5u.com熱心網友回復：

問題在于您宣告物件的方式。這段代碼只是創建了一個Instance包含所有資料的物件instance1。試試這個：

var info = [];

function calculateAmount(loanAmount, interest, loanTermYears) {
  var totalMonth = loanTermYears * 12;
  var montlyInterest = interest / 100 / 12;
  var temp = Math.pow(1   montlyInterest, totalMonth);
  var monthlyPayment = (loanAmount * montlyInterest * temp) / (temp - 1);
  var sum =  monthlyPayment * totalMonth;
  var totalAmount = sum;

  return totalAmount;
}

function Instance(instance) {
  this.Id = instance.Id;
  this.customerName = instance.customerName;
  this.phoneNumber = instance.phoneNumber;
  this.address = instance.address;
  this.loanAmount = instance.loanAmount;
  this.interest = instance.interest;
  this.loanTermYears = instance.loanTermYears;
  this.loanType = instance.loanType;
  this.description = instance.description;
  this.calculatedLoanAmount = calculateAmount(
    this.loanAmount,
    this.interest,
    this.loanTermYears
  );
}

var instanceParams = {
  Id: 0,
  customerName: "Khawaja Sardar",
  phoneNumber: "745-544-7777",
  address: "New York, NY",
  loanAmount: 5000,
  interest: 6.0,
  loanTermYears: 5,
  loanType: "APR",
  description: "Loan domain for instance1"
};

const instance1 = new Instance(instanceParams);

info.push(instance1);

console.log(info[0]);

uj5u.com熱心網友回復：

如果你洗掉了第二行，你會得到一個錯誤，比如 'cannot read properties of undefined (reading "loanAmount")'因為instance1還沒有定義。如果要根據物件包含的其他鍵設定物件的鍵，則需要在創建物件后進行，例如

var instance1 = {
...
}
instance1.calculatedLoanAmount = calculateLoanAmount(instance1.loanAmount, instance1.interest, instance1.loanTermYears)

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標籤：javascript

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