计算 JavaScript 对象中特定值的频率

Question

我有一个结构如下的 JavaScript 对象：

var subject = {all: "inactive",firstSingular: "active", secondarySingular: "inactive",thirdSingular: "active",firstPlural: "inactive", secondaryPlural: "inactive",thirdPlural: "inactive"

我想计算该对象内“active”值的实例数（即返回2）。我当然可以编写一个函数来迭代对象并计算值，尽管我想知道是否有更简洁的方法在 JavaScript 中执行此操作（在 1 行中），类似于 python 中的 collections.Counter 函数。

Answer 1

使用 Object#values 和 Array#reduce：

const subjects = { all: "inactive", firstSingular: "active", secondSingular: "inactive", thirdSingular: "active", firstPlural: "inactive", secondPlural: "inactive", thirdPlural: "inactive" };

const count = Object.values(subjects).reduce((total, value) => value === 'active' ? total + 1 : total, 0);

console.log(count);

使用 Array#filter< 的另一个解决方案/code>而不是减少：

const subjects = { all: "inactive", firstSingular: "active", secondSingular: "inactive", thirdSingular: "active", firstPlural: "inactive", secondPlural: "inactive", thirdPlural: "inactive" };

const count = Object.values(subjects).filter(value => value === 'active').length;

console.log(count);

Answer 2

另一种可能的解决方案是使用 filter 并获取结果的长度

var subjects = {all: "inactive", firstSingular: "active",secondSingular:"inactive", thirdSingular: "active", firstPlural: "inactive",secondPlural: "inactive", thirdPlural: "inactive"}

var res = Object.values(subjects).filter((val) => val === 'active').length

console.log(res)