对存储在数组中的对象的值求和

Question

我是 JavaScript 新手，我已经尝试了很多东西。我必须对函数内每个人的所有值（等级）求和。所以当我用

在外面调用函数时

console.log(totalNumberOfGrades(// I have to put here any of the three person objects... ));

所以函数内部可以对值求和。我在循环中使用.reduce 和for...进行了尝试，但是当我使用数组allPerson 时，我无法弄清楚如何访问objects 属性的值。感谢您的帮助，我会继续学习。

var person1 = {
    gradeMath: 2,
    gradeBio: 3,
    gradeEnglish: 1
};

var person2 = {
    gradeMath: 1,
    gradeBio: 2,
    gradeEnglish: 2
};

var person3 = {
    gradeMath: 3,
    gradeBio: 4,
    gradeEnglish: 3
};

var allPerson = [person1, person2, person3];

function totalNumberOfGrades(person) {
    // return the sum of grades for each person

}

结果如下所示：

console.log(totalNumberOfGrades(person1); = 6

Answer 1

在Object.values 上使用forEach

var person1 = {
    gradeMath: 2,
    gradeBio: 3,
    gradeEnglish: 1
};

function totalNumberOfGrades(person) {
  let sum = 0;
  Object.values(person).forEach(val => (sum += val));
  return sum;
}

console.log(totalNumberOfGrades(person1));

Answer 2

我假设你想对每个对象的每个等级求和

var person1 = {
  gradeMath: 2,
  gradeBio: 3,
  gradeEnglish: 1
};

var person2 = {
  gradeMath: 1,
  gradeBio: 2,
  gradeEnglish: 2
};

var person3 = {
  gradeMath: 3,
  gradeBio: 4,
  gradeEnglish: 3
};

var allPerson = [person1, person2, person3];

const result = allPerson.reduce((acc, x) => {
  const sumAllGrades = Object.values(x).reduce((acc, y) => acc + y, 0);
  return acc + sumAllGrades;
}, 0)
console.log(result)

Answer 3

您可以使用Object.values 和Array.reduce prototype。

function totalNumberOfGrades(person) { // return the sum of grades for each person
  return Object.values(person) // return array: [2, 3, 1] with person1
               .reduce((total, grade) => total + grade, 0)
}