按 JavaScript 数组对象分组
javascriptweb developmentfront end technologyobject oriented programming
假设我们有一个数组数组，其中包含一些学生在某些科目的成绩，例如 −
const arr = [ ["English", 52], ["Hindi", 154], ["Hindi", 241], ["Spanish", 10], ["French", 65], ["German", 98], ["Russian", 10] ];
我们需要编写一个 JavaScript 函数，该函数接受一个这样的数组并返回一个对象对象。
返回对象应包含每个唯一主题的对象，并且该对象应包含该语言出现的次数、总分总和和平均分等信息。
示例
其代码为 −
const arr = [
["English", 52],
["Hindi", 154],
["Hindi", 241],
["Spanish", 10],
["French", 65],
["German", 98],
["Russian", 10]
];
const groupSubjects = arr => {
const grouped = arr.reduce((acc, val) => {
const [key, total] = val;
if(!acc.hasOwnProperty(key)){
acc[key] = {
'count': 0,
'total': 0
};
};
const accuKey = acc[key];
accuKey['count']++;
accuKey['total'] += total;
accuKey['average'] = total / accuKey['count'];
return acc;
}, {});
return grouped;
};
console.log(groupSubjects(arr));
输出
控制台中的输出将是 −
{
English: { count: 1, total: 52, average: 52 },
Hindi: { count: 2, total: 395, average: 120.5 },
Spanish: { count: 1, total: 10, average: 10 },
French: { count: 1, total: 65, average: 65 },
German: { count: 1, total: 98, average: 98 },
Russian: { count: 1, total: 10, average: 10 }
}
