如何根据另一个对象中给出的规范过滤对象？
How to filter an object according to specification given in another object?
我想根据另一个对象中给出的规范从 对象 中过滤掉数据。
例如，考虑以下 BandAndAlbums 对象，该对象包含有关 3 个乐队的 raw 数据（Beatles、史密斯飞船和女王):
const BandAndAlbums = {
beatles: {
origin: 'liverpool',
genres: ['rock', 'pop', 'beat', 'psychedelia'],
labels: ['parlophone', 'apple', 'capitol'],
discography: {
yellowSubmarine: {
released: 1969,
length: 39.16,
producer: 'george martin',
label: 'apple',
},
rubberSoul: {
released: 1965,
length: 34.55,
producer: 'george martin',
label: 'parlophone',
},
letItBe: {
released: 1970,
length: 35.1,
producer: 'phil spector',
label: 'apple',
},
revolver: {
released: 1966,
length: 35.01,
producer: 'george martin',
label: 'parlophone',
},
},
},
aerosmith: {
origin: 'boston',
genres: [
'hard rock',
'blues rock',
'rock and roll',
'glam metal',
'heavy metal',
],
labels: ['columbia', 'geffen'],
discography: {
doneWithMirrors: {
released: 1985,
length: 35.42,
producer: 'ted templeman',
label: 'geffen',
},
rocks: {
released: 1976,
length: 34.31,
producer: 'jack douglas',
label: 'columbia',
},
nineLives: {
released: 1997,
length: 62.54,
producer: 'kevin shirley',
label: 'columbia',
},
},
},
queen: {
origin: 'london',
genres: ['rock'],
labels: [
'emi',
'parlophone',
'elektra',
'capitol',
'hollywood',
'island',
'virgin emi',
],
discography: {
aNightAtTheOpera: {
released: 1975,
length: 43.08,
producer: 'roy thomas baker',
label: 'emi',
},
newsOfTheWorld: {
released: 1977,
length: 39.1,
producer: 'queen',
label: 'emi',
},
aKindOfMagic: {
released: 1986,
length: 40.42,
producer: 'queen',
label: 'emi',
},
},
},
};
我想过滤 BandAndAlbums，以每个乐队仅选择专辑结束，并且每个乐队中只有 length 和 producer 属性。
如果我在下面指定我想要的相册requestedAlbums:
const requestedAlbums = {
queen: ['aNightAtTheOpera', 'aKindOfMagic'],
beatles: ['rubberSoul', 'letItBe', 'revolver'],
aerosmith: ['doneWithMirrors', 'nineLives'],
};
我如何过滤 BandAndAlbums 它，并创建一个新对象，每个所选专辑只有 length 和 producer？
期望输出
const desiredOutput = {
beatles: {
rubberSoul: {
length: 34.55,
producer: 'george martin',
},
letItBe: {
length: 35.1,
producer: 'phil spector',
},
revolver: {
length: 35.01,
producer: 'george martin',
},
},
aerosmith: {
doneWithMirrors: {
length: 35.42,
producer: 'ted templeman',
},
nineLives: {
length: 62.54,
producer: 'kevin shirley',
},
},
queen: {
aNightAtTheOpera: {
length: 43.08,
producer: 'roy thomas baker',
},
aKindOfMagic: {
length: 40.42,
producer: 'queen',
},
},
};
编辑
为了解决下面的评论，我要补充一点，我熟悉将对象转换为数组的过程（使用 Object.entries()），从而促进数组方法的使用（例如，.filter(), .map(), 等等), 最后用 Object.fromEntries().
转换回一个对象
不幸的是，在这种情况下，我有点不知道如何做我需要做的事情。我假设为了快速启动，我需要按照以下方式做一些事情：
Object.entries(BandAndAlbums).map( ([k, v]) => [k, v.discography])
（但后来我明白了 undefined）
// [ [ 'queen', undefined ],
// [ 'beatles', undefined ],
// [ 'aerosmith', undefined ] ]
所以，如果有人能引导我走向正确的方向，我将不胜感激。谢谢。
我认为下面的函数可以解决您的需求：
const BandAndAlbums = {
beatles: {
origin: 'liverpool',
genres: ['rock', 'pop', 'beat', 'psychedelia'],
labels: ['parlophone', 'apple', 'capitol'],
discography: {
yellowSubmarine: {
released: 1969,
length: 39.16,
producer: 'george martin',
label: 'apple',
},
rubberSoul: {
released: 1965,
length: 34.55,
producer: 'george martin',
label: 'parlophone',
},
letItBe: {
released: 1970,
length: 35.1,
producer: 'phil spector',
label: 'apple',
},
revolver: {
released: 1966,
length: 35.01,
producer: 'george martin',
label: 'parlophone',
},
},
},
aerosmith: {
origin: 'boston',
genres: [
'hard rock',
'blues rock',
'rock and roll',
'glam metal',
'heavy metal',
],
labels: ['columbia', 'geffen'],
discography: {
doneWithMirrors: {
released: 1985,
length: 35.42,
producer: 'ted templeman',
label: 'geffen',
},
rocks: {
released: 1976,
length: 34.31,
producer: 'jack douglas',
label: 'columbia',
},
nineLives: {
released: 1997,
length: 62.54,
producer: 'kevin shirley',
label: 'columbia',
},
},
},
queen: {
origin: 'london',
genres: ['rock'],
labels: [
'emi',
'parlophone',
'elektra',
'capitol',
'hollywood',
'island',
'virgin emi',
],
discography: {
aNightAtTheOpera: {
released: 1975,
length: 43.08,
producer: 'roy thomas baker',
label: 'emi',
},
newsOfTheWorld: {
released: 1977,
length: 39.1,
producer: 'queen',
label: 'emi',
},
aKindOfMagic: {
released: 1986,
length: 40.42,
producer: 'queen',
label: 'emi',
},
},
},
};
const requestedAlbums = {
queen: ['aNightAtTheOpera', 'aKindOfMagic'],
beatles: ['rubberSoul', 'letItBe', 'revolver'],
aerosmith: ['doneWithMirrors', 'nineLives'],
};
// This is your desired funciton
var filterAlbum=(a,r)=>{
var ou = {};
for(let ri in r){
if(typeof a[ri]!== 'undefined'){
var our = {};
for(let di of r[ri]){
if(typeof a[ri].discography[di]!=='undefined'){
let dis = a[ri].discography[di];
our[di]={length:dis.length,producer:dis.producer};
}
}
ou[ri] = our;
}
}
return ou;
}
const desiredOutput = filterAlbum(BandAndAlbums,requestedAlbums);
console.log(desiredOutput);
如果您需要更多过滤器，可以在这里询问更多。
谢谢
您可以通过 Array.reduce() 和 Array.entries() 的组合轻松实现此目的：
const BandAndAlbums = {
beatles: {
origin: 'liverpool',
genres: ['rock', 'pop', 'beat', 'psychedelia'],
labels: ['parlophone', 'apple', 'capitol'],
discography: {
yellowSubmarine: {
released: 1969,
length: 39.16,
producer: 'george martin',
label: 'apple',
},
rubberSoul: {
released: 1965,
length: 34.55,
producer: 'george martin',
label: 'parlophone',
},
letItBe: {
released: 1970,
length: 35.1,
producer: 'phil spector',
label: 'apple',
},
revolver: {
released: 1966,
length: 35.01,
producer: 'george martin',
label: 'parlophone',
},
},
},
aerosmith: {
origin: 'boston',
genres: [
'hard rock',
'blues rock',
'rock and roll',
'glam metal',
'heavy metal',
],
labels: ['columbia', 'geffen'],
discography: {
doneWithMirrors: {
released: 1985,
length: 35.42,
producer: 'ted templeman',
label: 'geffen',
},
rocks: {
released: 1976,
length: 34.31,
producer: 'jack douglas',
label: 'columbia',
},
nineLives: {
released: 1997,
length: 62.54,
producer: 'kevin shirley',
label: 'columbia',
},
},
},
queen: {
origin: 'london',
genres: ['rock'],
labels: [
'emi',
'parlophone',
'elektra',
'capitol',
'hollywood',
'island',
'virgin emi',
],
discography: {
aNightAtTheOpera: {
released: 1975,
length: 43.08,
producer: 'roy thomas baker',
label: 'emi',
},
newsOfTheWorld: {
released: 1977,
length: 39.1,
producer: 'queen',
label: 'emi',
},
aKindOfMagic: {
released: 1986,
length: 40.42,
producer: 'queen',
label: 'emi',
},
},
},
};
const requestedAlbums = {
queen: ['aNightAtTheOpera', 'aKindOfMagic'],
beatles: ['rubberSoul', 'letItBe', 'revolver'],
aerosmith: ['doneWithMirrors', 'nineLives'],
};
const result2 = Object.entries(requestedAlbums).reduce((tot, [k, v]) => {
// all songs of the band
const allSongs = BandAndAlbums[k].discography
// take chosen ones
const chosenSongs = v.reduce((chosen, song) => {
chosen[song] = {
length: allSongs[song].length,
producer: allSongs[song].producer
}
return chosen
}, {})
// add to total
tot[k] = chosenSongs
return tot
}, {})
console.log(result2)
可以用Object.entries得到一个pair数组，然后做所有的映射和过滤，最后把得到的pair数组转回Object.fromEntries的result对象。
Object.fromEntries 也可以应用于嵌套级别以生成嵌套对象：
const BandAndAlbums = {beatles: {origin: 'liverpool',genres: ['rock', 'pop', 'beat', 'psychedelia'],labels: ['parlophone', 'apple', 'capitol'],discography: {yellowSubmarine: {released: 1969,length: 39.16,producer: 'george martin',label: 'apple',},rubberSoul: {released: 1965,length: 34.55,producer: 'george martin',label: 'parlophone',},letItBe: {released: 1970,length: 35.1,producer: 'phil spector',label: 'apple',},revolver: {released: 1966,length: 35.01,producer: 'george martin',label: 'parlophone',},},},aerosmith: {origin: 'boston',genres: ['hard rock','blues rock','rock and roll','glam metal','heavy metal',],labels: ['columbia', 'geffen'],discography: {doneWithMirrors: {released: 1985,length: 35.42,producer: 'ted templeman',label: 'geffen',},rocks: {released: 1976,length: 34.31,producer: 'jack douglas',label: 'columbia',},nineLives: {released: 1997,length: 62.54,producer: 'kevin shirley',label: 'columbia',},},},queen: {origin: 'london',genres: ['rock'],labels: ['emi','parlophone','elektra','capitol','hollywood','island','virgin emi',],discography: {aNightAtTheOpera: {released: 1975,length: 43.08,producer: 'roy thomas baker',label: 'emi',},newsOfTheWorld: {released: 1977,length: 39.1,producer: 'queen',label: 'emi',},aKindOfMagic: {released: 1986,length: 40.42,producer: 'queen',label: 'emi',},},},};
const requestedAlbums = {queen: ['aNightAtTheOpera', 'aKindOfMagic'],beatles: ['rubberSoul', 'letItBe', 'revolver'],aerosmith: ['doneWithMirrors', 'nineLives'],};
const output = Object.fromEntries(
Object.entries(requestedAlbums).map(([band, albums]) => [
band,
Object.fromEntries(
albums.map(album => [album, BandAndAlbums[band].discography[album]])
.map(([album, {length, producer}]) => [album, {length, producer}])
)
])
);
console.log(output);
这可以工作，利用对象和数组函数。
const filter = (BandAndAlbums, requestedAlbums) => Object.fromEntries(
Object.entries(requestedAlbums).map(([name, list]) => [name, Object.fromEntries(
list.map(entry => [entry, BandAndAlbums[name]?.discography[entry]])
.filter(([entry, discography]) => discography)
.map(([entry, {length, producer}]) => [entry, {length, producer}]
))]
)
);
const BandAndAlbums = {
beatles: {
origin: 'liverpool',
genres: ['rock', 'pop', 'beat', 'psychedelia'],
labels: ['parlophone', 'apple', 'capitol'],
discography: {
yellowSubmarine: {
released: 1969,
length: 39.16,
producer: 'george martin',
label: 'apple',
},
rubberSoul: {
released: 1965,
length: 34.55,
producer: 'george martin',
label: 'parlophone',
},
letItBe: {
released: 1970,
length: 35.1,
producer: 'phil spector',
label: 'apple',
},
revolver: {
released: 1966,
length: 35.01,
producer: 'george martin',
label: 'parlophone',
},
},
},
aerosmith: {
origin: 'boston',
genres: [
'hard rock',
'blues rock',
'rock and roll',
'glam metal',
'heavy metal',
],
labels: ['columbia', 'geffen'],
discography: {
doneWithMirrors: {
released: 1985,
length: 35.42,
producer: 'ted templeman',
label: 'geffen',
},
rocks: {
released: 1976,
length: 34.31,
producer: 'jack douglas',
label: 'columbia',
},
nineLives: {
released: 1997,
length: 62.54,
producer: 'kevin shirley',
label: 'columbia',
},
},
},
queen: {
origin: 'london',
genres: ['rock'],
labels: [
'emi',
'parlophone',
'elektra',
'capitol',
'hollywood',
'island',
'virgin emi',
],
discography: {
aNightAtTheOpera: {
released: 1975,
length: 43.08,
producer: 'roy thomas baker',
label: 'emi',
},
newsOfTheWorld: {
released: 1977,
length: 39.1,
producer: 'queen',
label: 'emi',
},
aKindOfMagic: {
released: 1986,
length: 40.42,
producer: 'queen',
label: 'emi',
},
},
},
};
const requestedAlbums = {
queen: ['aNightAtTheOpera', 'aKindOfMagic'],
beatles: ['rubberSoul', 'letItBe', 'revolver'],
aerosmith: ['doneWithMirrors', 'nineLives'],
};
console.log(filter(BandAndAlbums, requestedAlbums));
我想根据另一个对象中给出的规范从 对象 中过滤掉数据。
例如，考虑以下 BandAndAlbums 对象，该对象包含有关 3 个乐队的 raw 数据（Beatles、史密斯飞船和女王):
const BandAndAlbums = {
beatles: {
origin: 'liverpool',
genres: ['rock', 'pop', 'beat', 'psychedelia'],
labels: ['parlophone', 'apple', 'capitol'],
discography: {
yellowSubmarine: {
released: 1969,
length: 39.16,
producer: 'george martin',
label: 'apple',
},
rubberSoul: {
released: 1965,
length: 34.55,
producer: 'george martin',
label: 'parlophone',
},
letItBe: {
released: 1970,
length: 35.1,
producer: 'phil spector',
label: 'apple',
},
revolver: {
released: 1966,
length: 35.01,
producer: 'george martin',
label: 'parlophone',
},
},
},
aerosmith: {
origin: 'boston',
genres: [
'hard rock',
'blues rock',
'rock and roll',
'glam metal',
'heavy metal',
],
labels: ['columbia', 'geffen'],
discography: {
doneWithMirrors: {
released: 1985,
length: 35.42,
producer: 'ted templeman',
label: 'geffen',
},
rocks: {
released: 1976,
length: 34.31,
producer: 'jack douglas',
label: 'columbia',
},
nineLives: {
released: 1997,
length: 62.54,
producer: 'kevin shirley',
label: 'columbia',
},
},
},
queen: {
origin: 'london',
genres: ['rock'],
labels: [
'emi',
'parlophone',
'elektra',
'capitol',
'hollywood',
'island',
'virgin emi',
],
discography: {
aNightAtTheOpera: {
released: 1975,
length: 43.08,
producer: 'roy thomas baker',
label: 'emi',
},
newsOfTheWorld: {
released: 1977,
length: 39.1,
producer: 'queen',
label: 'emi',
},
aKindOfMagic: {
released: 1986,
length: 40.42,
producer: 'queen',
label: 'emi',
},
},
},
};
我想过滤 BandAndAlbums，以每个乐队仅选择专辑结束，并且每个乐队中只有 length 和 producer 属性。
如果我在下面指定我想要的相册requestedAlbums:
const requestedAlbums = {
queen: ['aNightAtTheOpera', 'aKindOfMagic'],
beatles: ['rubberSoul', 'letItBe', 'revolver'],
aerosmith: ['doneWithMirrors', 'nineLives'],
};
我如何过滤 BandAndAlbums 它，并创建一个新对象，每个所选专辑只有 length 和 producer？
期望输出
const desiredOutput = {
beatles: {
rubberSoul: {
length: 34.55,
producer: 'george martin',
},
letItBe: {
length: 35.1,
producer: 'phil spector',
},
revolver: {
length: 35.01,
producer: 'george martin',
},
},
aerosmith: {
doneWithMirrors: {
length: 35.42,
producer: 'ted templeman',
},
nineLives: {
length: 62.54,
producer: 'kevin shirley',
},
},
queen: {
aNightAtTheOpera: {
length: 43.08,
producer: 'roy thomas baker',
},
aKindOfMagic: {
length: 40.42,
producer: 'queen',
},
},
};
编辑
为了解决下面的评论，我要补充一点，我熟悉将对象转换为数组的过程（使用 Object.entries()），从而促进数组方法的使用（例如，.filter(), .map(), 等等), 最后用 Object.fromEntries().
不幸的是，在这种情况下，我有点不知道如何做我需要做的事情。我假设为了快速启动，我需要按照以下方式做一些事情：
Object.entries(BandAndAlbums).map( ([k, v]) => [k, v.discography])
（但后来我明白了 undefined）
// [ [ 'queen', undefined ],
// [ 'beatles', undefined ],
// [ 'aerosmith', undefined ] ]
所以，如果有人能引导我走向正确的方向，我将不胜感激。谢谢。
我认为下面的函数可以解决您的需求：
const BandAndAlbums = {
beatles: {
origin: 'liverpool',
genres: ['rock', 'pop', 'beat', 'psychedelia'],
labels: ['parlophone', 'apple', 'capitol'],
discography: {
yellowSubmarine: {
released: 1969,
length: 39.16,
producer: 'george martin',
label: 'apple',
},
rubberSoul: {
released: 1965,
length: 34.55,
producer: 'george martin',
label: 'parlophone',
},
letItBe: {
released: 1970,
length: 35.1,
producer: 'phil spector',
label: 'apple',
},
revolver: {
released: 1966,
length: 35.01,
producer: 'george martin',
label: 'parlophone',
},
},
},
aerosmith: {
origin: 'boston',
genres: [
'hard rock',
'blues rock',
'rock and roll',
'glam metal',
'heavy metal',
],
labels: ['columbia', 'geffen'],
discography: {
doneWithMirrors: {
released: 1985,
length: 35.42,
producer: 'ted templeman',
label: 'geffen',
},
rocks: {
released: 1976,
length: 34.31,
producer: 'jack douglas',
label: 'columbia',
},
nineLives: {
released: 1997,
length: 62.54,
producer: 'kevin shirley',
label: 'columbia',
},
},
},
queen: {
origin: 'london',
genres: ['rock'],
labels: [
'emi',
'parlophone',
'elektra',
'capitol',
'hollywood',
'island',
'virgin emi',
],
discography: {
aNightAtTheOpera: {
released: 1975,
length: 43.08,
producer: 'roy thomas baker',
label: 'emi',
},
newsOfTheWorld: {
released: 1977,
length: 39.1,
producer: 'queen',
label: 'emi',
},
aKindOfMagic: {
released: 1986,
length: 40.42,
producer: 'queen',
label: 'emi',
},
},
},
};
const requestedAlbums = {
queen: ['aNightAtTheOpera', 'aKindOfMagic'],
beatles: ['rubberSoul', 'letItBe', 'revolver'],
aerosmith: ['doneWithMirrors', 'nineLives'],
};
// This is your desired funciton
var filterAlbum=(a,r)=>{
var ou = {};
for(let ri in r){
if(typeof a[ri]!== 'undefined'){
var our = {};
for(let di of r[ri]){
if(typeof a[ri].discography[di]!=='undefined'){
let dis = a[ri].discography[di];
our[di]={length:dis.length,producer:dis.producer};
}
}
ou[ri] = our;
}
}
return ou;
}
const desiredOutput = filterAlbum(BandAndAlbums,requestedAlbums);
console.log(desiredOutput);
如果您需要更多过滤器，可以在这里询问更多。 谢谢
您可以通过 Array.reduce() 和 Array.entries() 的组合轻松实现此目的：
const BandAndAlbums = {
beatles: {
origin: 'liverpool',
genres: ['rock', 'pop', 'beat', 'psychedelia'],
labels: ['parlophone', 'apple', 'capitol'],
discography: {
yellowSubmarine: {
released: 1969,
length: 39.16,
producer: 'george martin',
label: 'apple',
},
rubberSoul: {
released: 1965,
length: 34.55,
producer: 'george martin',
label: 'parlophone',
},
letItBe: {
released: 1970,
length: 35.1,
producer: 'phil spector',
label: 'apple',
},
revolver: {
released: 1966,
length: 35.01,
producer: 'george martin',
label: 'parlophone',
},
},
},
aerosmith: {
origin: 'boston',
genres: [
'hard rock',
'blues rock',
'rock and roll',
'glam metal',
'heavy metal',
],
labels: ['columbia', 'geffen'],
discography: {
doneWithMirrors: {
released: 1985,
length: 35.42,
producer: 'ted templeman',
label: 'geffen',
},
rocks: {
released: 1976,
length: 34.31,
producer: 'jack douglas',
label: 'columbia',
},
nineLives: {
released: 1997,
length: 62.54,
producer: 'kevin shirley',
label: 'columbia',
},
},
},
queen: {
origin: 'london',
genres: ['rock'],
labels: [
'emi',
'parlophone',
'elektra',
'capitol',
'hollywood',
'island',
'virgin emi',
],
discography: {
aNightAtTheOpera: {
released: 1975,
length: 43.08,
producer: 'roy thomas baker',
label: 'emi',
},
newsOfTheWorld: {
released: 1977,
length: 39.1,
producer: 'queen',
label: 'emi',
},
aKindOfMagic: {
released: 1986,
length: 40.42,
producer: 'queen',
label: 'emi',
},
},
},
};
const requestedAlbums = {
queen: ['aNightAtTheOpera', 'aKindOfMagic'],
beatles: ['rubberSoul', 'letItBe', 'revolver'],
aerosmith: ['doneWithMirrors', 'nineLives'],
};
const result2 = Object.entries(requestedAlbums).reduce((tot, [k, v]) => {
// all songs of the band
const allSongs = BandAndAlbums[k].discography
// take chosen ones
const chosenSongs = v.reduce((chosen, song) => {
chosen[song] = {
length: allSongs[song].length,
producer: allSongs[song].producer
}
return chosen
}, {})
// add to total
tot[k] = chosenSongs
return tot
}, {})
console.log(result2)
可以用Object.entries得到一个pair数组，然后做所有的映射和过滤，最后把得到的pair数组转回Object.fromEntries的result对象。
Object.fromEntries 也可以应用于嵌套级别以生成嵌套对象：
const BandAndAlbums = {beatles: {origin: 'liverpool',genres: ['rock', 'pop', 'beat', 'psychedelia'],labels: ['parlophone', 'apple', 'capitol'],discography: {yellowSubmarine: {released: 1969,length: 39.16,producer: 'george martin',label: 'apple',},rubberSoul: {released: 1965,length: 34.55,producer: 'george martin',label: 'parlophone',},letItBe: {released: 1970,length: 35.1,producer: 'phil spector',label: 'apple',},revolver: {released: 1966,length: 35.01,producer: 'george martin',label: 'parlophone',},},},aerosmith: {origin: 'boston',genres: ['hard rock','blues rock','rock and roll','glam metal','heavy metal',],labels: ['columbia', 'geffen'],discography: {doneWithMirrors: {released: 1985,length: 35.42,producer: 'ted templeman',label: 'geffen',},rocks: {released: 1976,length: 34.31,producer: 'jack douglas',label: 'columbia',},nineLives: {released: 1997,length: 62.54,producer: 'kevin shirley',label: 'columbia',},},},queen: {origin: 'london',genres: ['rock'],labels: ['emi','parlophone','elektra','capitol','hollywood','island','virgin emi',],discography: {aNightAtTheOpera: {released: 1975,length: 43.08,producer: 'roy thomas baker',label: 'emi',},newsOfTheWorld: {released: 1977,length: 39.1,producer: 'queen',label: 'emi',},aKindOfMagic: {released: 1986,length: 40.42,producer: 'queen',label: 'emi',},},},};
const requestedAlbums = {queen: ['aNightAtTheOpera', 'aKindOfMagic'],beatles: ['rubberSoul', 'letItBe', 'revolver'],aerosmith: ['doneWithMirrors', 'nineLives'],};
const output = Object.fromEntries(
Object.entries(requestedAlbums).map(([band, albums]) => [
band,
Object.fromEntries(
albums.map(album => [album, BandAndAlbums[band].discography[album]])
.map(([album, {length, producer}]) => [album, {length, producer}])
)
])
);
console.log(output);
这可以工作，利用对象和数组函数。
const filter = (BandAndAlbums, requestedAlbums) => Object.fromEntries(
Object.entries(requestedAlbums).map(([name, list]) => [name, Object.fromEntries(
list.map(entry => [entry, BandAndAlbums[name]?.discography[entry]])
.filter(([entry, discography]) => discography)
.map(([entry, {length, producer}]) => [entry, {length, producer}]
))]
)
);
const BandAndAlbums = {
beatles: {
origin: 'liverpool',
genres: ['rock', 'pop', 'beat', 'psychedelia'],
labels: ['parlophone', 'apple', 'capitol'],
discography: {
yellowSubmarine: {
released: 1969,
length: 39.16,
producer: 'george martin',
label: 'apple',
},
rubberSoul: {
released: 1965,
length: 34.55,
producer: 'george martin',
label: 'parlophone',
},
letItBe: {
released: 1970,
length: 35.1,
producer: 'phil spector',
label: 'apple',
},
revolver: {
released: 1966,
length: 35.01,
producer: 'george martin',
label: 'parlophone',
},
},
},
aerosmith: {
origin: 'boston',
genres: [
'hard rock',
'blues rock',
'rock and roll',
'glam metal',
'heavy metal',
],
labels: ['columbia', 'geffen'],
discography: {
doneWithMirrors: {
released: 1985,
length: 35.42,
producer: 'ted templeman',
label: 'geffen',
},
rocks: {
released: 1976,
length: 34.31,
producer: 'jack douglas',
label: 'columbia',
},
nineLives: {
released: 1997,
length: 62.54,
producer: 'kevin shirley',
label: 'columbia',
},
},
},
queen: {
origin: 'london',
genres: ['rock'],
labels: [
'emi',
'parlophone',
'elektra',
'capitol',
'hollywood',
'island',
'virgin emi',
],
discography: {
aNightAtTheOpera: {
released: 1975,
length: 43.08,
producer: 'roy thomas baker',
label: 'emi',
},
newsOfTheWorld: {
released: 1977,
length: 39.1,
producer: 'queen',
label: 'emi',
},
aKindOfMagic: {
released: 1986,
length: 40.42,
producer: 'queen',
label: 'emi',
},
},
},
};
const requestedAlbums = {
queen: ['aNightAtTheOpera', 'aKindOfMagic'],
beatles: ['rubberSoul', 'letItBe', 'revolver'],
aerosmith: ['doneWithMirrors', 'nineLives'],
};
console.log(filter(BandAndAlbums, requestedAlbums));