JavaScript程序，根据Subject组显示名称列表

Question

let a = 
[
{
Name: 'Josh',
Subject: ['Biology', 'Chemistry'],  
},
{
Name: 'James',
Subject: ['Chemistry', 'Physics'],
},
{
Name: 'Mary',
Subject: ['Physics', 'Mathematics'],
},
]
const result = a.reduce((groupedSubject, person) => {
const Subject = person.Subject
if(groupedSubject[Subject]== null) groupedSubject[Subject] = []
groupedSubject[Subject].push(person)
return groupedSubject
}, {})
console.log(result)

我可以根据主题进行分组，但主题是一个数组。我怎么组由各个科目吗?

Answer 1

您还需要迭代Sports数组。

const
data = [{ Name: 'Ravindra', Sports: ['Chess', 'Cricket'] }, { Name: 'Ravi', Sports: ['Cricket', 'Football'] }, { Name: 'Rishabh', Sports: ['Table-Tennis', 'Football'] }],
result = data.reduce((groupedSports, person) => {
person.Sports.forEach(sport => {
groupedSports[sport] ??= [];
groupedSports[sport].push(person.Name);
})
return groupedSports;
}, {});
console.log(result);

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Answer 2

您可以遍历所有体育项目并检查它是否已经存在，如果不存在，则展开所有当前条目并将新的人员Name添加到数组中。

let a = [{
Name: 'Ravindra',
Sports: ['Chess', 'Cricket'],
},
{
Name: 'Ravi',
Sports: ['Cricket', 'Football'],
},
{
Name: 'Rishabh',
Sports: ['Table-Tennis', 'Football'],
},
]
const result = a.reduce((groupedSports, person) => {
person.Sports.forEach((sport) => {
groupedSports[sport] = groupedSports?.[sport]
? [...groupedSports[sport], person.Name]
: [person.Name];
});
return groupedSports;
}, {});
console.log(result)