有没有一种方法可以跨对象选择相同的变量并将它们的值有效地相加？

Question

让我说我想从六个对象中找到本金总额，有没有一种方法可以快速完成，而不是按照我的方式进行，这似乎是一种不好的做法，如果数字是多少，将很难使用的对象更多。

数组

var monthlyInfo =[{Date: "Jan 2020", Balance: 747798, Mortgage: 2827, Principal: 2202, Interest: 625}
{Date: "Feb 2020", Balance: 745594, Mortgage: 2827, Principal: 2204, Interest: 623}
{Date: "Mar 2020", Balance: 743388, Mortgage: 2827, Principal: 2206, Interest: 621}
{Date: "Apr 2020", Balance: 741181, Mortgage: 2827, Principal: 2208, Interest: 619}
{Date: "May 2020", Balance: 738972, Mortgage: 2827, Principal: 2209, Interest: 618}
{Date: "Jun 2020", Balance: 736760, Mortgage: 2827, Principal: 2211, Interest: 616}]

当前代码

monthlyInfo[0].Principal + monthlyInfo[1].Principal + monthlyInfo[2].Principal + monthlyInfo[3].Principal + monthlyInfo[4].Principal + monthlyInfo[5].Principal 

Answer 1

只需像这样使用reduce：

const principalTotal = monthlyInfo.reduce((a, { Principal }) => a + Principal, 0);

摘要：

var monthlyInfo=[{Date:"Jan 2020",Balance:747798,Mortgage:2827,Principal:2202,Interest:625},{Date:"Feb 2020",Balance:745594,Mortgage:2827,Principal:2204,Interest:623},{Date:"Mar 2020",Balance:743388,Mortgage:2827,Principal:2206,Interest:621},{Date:"Apr 2020",Balance:741181,Mortgage:2827,Principal:2208,Interest:619},{Date:"May 2020",Balance:738972,Mortgage:2827,Principal:2209,Interest:618},{Date:"Jun 2020",Balance:736760,Mortgage:2827,Principal:2211,Interest:616}];

const principalTotal = monthlyInfo.reduce((a, { Principal }) => a + Principal, 0);

console.log(principalTotal);