我需要找到這個陣列中所有寵物的總年齡。我試過這段代碼，但得到一個 NaN 輸出。我如何訪問寵物的年齡以獲得總和？
我試過這段代碼，但得到一個 NaN 輸出。
const totalAgeAllPets = data.reduce((result, pet) => {
return result pet.pets.age},0)
console.log(totalAgeAllPets)
const data = [{
name: "mark",
age: 27,
from: "Chicago",
pets: [],
},
{
name: "greg",
age: 68,
from: "Auburn",
pets: [{
type: "rock",
name: "herbert",
age: 126003219,
}, ],
},
{
name: "ken",
age: 28,
from: "Naperville",
pets: [{
type: "cat",
name: "colby",
age: 1,
},
{
type: "dog",
name: "charlie",
age: 3,
},
{
type: "dog",
name: "william riker",
age: 1,
},
{
type: "dog",
name: "thomas riker",
age: 1,
},
],
},
{
name: "kristiana",
age: 47,
from: "Chicago",
pets: [],
},
{
name: "bryan",
age: 27,
from: "Lincoln Park Zoo",
pets: [{
type: "white tiger",
name: "arthur",
age: 3,
},
{
type: "silverback gorilla",
name: "tommy",
age: 4,
},
{
type: "guinea pig",
name: "kirk",
age: 1,
},
{
type: "hamster",
name: "spock",
age: 1,
},
{
type: "hamster",
name: "sarek",
age: 1,
},
{
type: "cat",
name: "quark",
age: 1,
},
{
type: "cat",
name: "kira nerys",
age: 1,
},
],
},
{
name: "anthony",
age: 31,
from: "Phoenix",
pets: [],
},
{
name: "stephanie",
age: 27,
from: "Chicago",
pets: [{
type: "dog",
name: "midnight",
age: 3,
}, ],
},
{
name: "david p",
age: 40,
from: "Lancaster",
pets: [{
type: "dog",
name: "quinn",
age: 8,
}, ],
},
{
name: "patrick",
age: 39,
from: "Poway",
pets: [{
type: "dog",
name: "hazel",
age: 7,
},
{
type: "cat",
name: "fredy perlman",
age: 13,
},
],
},
{
name: "david a",
age: 32,
from: "San Francisco",
pets: [{
type: "monstera",
name: "holey",
age: 1,
}, ],
},
{
name: "timm",
age: 32,
from: "Gainsville",
pets: [{
type: "goldfish",
name: "betsy",
age: 4,
}, ],
},
{
name: "conrad",
age: 101,
from: "Minneapolis",
pets: [],
},
{
name: "nate",
age: 14,
from: "Boston",
pets: [{
type: "cat",
name: "rosie",
age: 0.005,
},
{
type: "hermit crab",
name: "kermit",
age: 1, // 16 wow wtf
},
{
type: "dog",
name: "ernie",
age: 4,
},
{
type: "cat",
name: "kendrick lamar jr",
age: 6,
},
{
type: "cat",
name: "guinan",
age: 589,
},
{
type: "cat",
name: "beverly",
age: 1,
},
],
},
{
name: "temo",
age: 25,
from: "Osaka",
pets: [{
type: "dog",
name: "nacho",
age: 1,
},
{
type: "dog",
name: "belky",
age: 1,
},
{
type: "dog",
name: "janeway",
age: 4,
},
{
type: "dog",
name: "jean-luc",
age: 12,
},
{
type: "monkey",
name: "shin chan",
age: 1,
},
],
},
{
name: "griffin",
age: 22,
from: "Chicago",
pets: [{
type: "bearded dragon",
name: "ferg",
age: 3,
}, ],
},
{
name: "eman",
age: 20,
from: "Lake in the Hills",
pets: [{
type: "parakeet",
name: "sunny",
age: 400,
},
{
type: "parrot",
name: "vic fontaine",
age: 46,
},
{
type: "parrot",
name: "worf",
age: 48,
},
{
type: "cockatoo",
name: "spockatoo",
age: 33,
},
],
},
{
name: "jürgen",
age: 28,
from: "Chicago",
pets: [{
type: "cat",
name: "mija",
age: 6,
}, ],
},
{
name: "michele",
age: 33,
from: "Rome",
pets: [{
type: "cat",
name: "caesar", // "cheeto"
age: 3,
},
{
type: "cat",
name: "cleopatra",
age: 3,
},
{
type: "cat",
name: "tuvok",
age: 10,
},
{
type: "turtle",
name: "spock",
age: 13,
},
],
},
{
name: "mitchell",
age: 19,
from: "Iowa City",
pets: [{
type: "cat",
name: "eddie",
age: 7,
}, ],
},
{
name: "reuben",
age: 41,
from: "Durham",
pets: [{
type: "cat",
name: "nico",
age: 15,
},
{
type: "cat",
name: "rocky",
age: 5,
},
],
},
{
name: "fatima",
age: 24,
from: "Milwaukee",
pets: [{
type: "snake",
name: "reginald",
age: 12,
}, ],
},
];
const totalAgeAllPets = data.reduce((result, pet) => {
return result pet.pets.age;
}, 0);
console.log(totalAgeAllPets);有人可以指出我正確的方向嗎？
uj5u.com熱心網友回復：
data陣列中的每個物件也有嵌套陣列pets，因此您必須計算嵌套陣列的總和并將其添加到全域計數中：
const totalAgeAllPets = data.reduce((result, pet) => {
return result pet.pets.reduce((a, p) => a p.age, 0);
}, 0);
console.log(totalAgeAllPets);
顯示代碼片段
const data = [{
name: "mark",
age: 27,
from: "Chicago",
pets: [],
},
{
name: "greg",
age: 68,
from: "Auburn",
pets: [{
type: "rock",
name: "herbert",
age: 126003219,
}, ],
},
{
name: "ken",
age: 28,
from: "Naperville",
pets: [{
type: "cat",
name: "colby",
age: 1,
},
{
type: "dog",
name: "charlie",
age: 3,
},
{
type: "dog",
name: "william riker",
age: 1,
},
{
type: "dog",
name: "thomas riker",
age: 1,
},
],
},
{
name: "kristiana",
age: 47,
from: "Chicago",
pets: [],
},
{
name: "bryan",
age: 27,
from: "Lincoln Park Zoo",
pets: [{
type: "white tiger",
name: "arthur",
age: 3,
},
{
type: "silverback gorilla",
name: "tommy",
age: 4,
},
{
type: "guinea pig",
name: "kirk",
age: 1,
},
{
type: "hamster",
name: "spock",
age: 1,
},
{
type: "hamster",
name: "sarek",
age: 1,
},
{
type: "cat",
name: "quark",
age: 1,
},
{
type: "cat",
name: "kira nerys",
age: 1,
},
],
},
{
name: "anthony",
age: 31,
from: "Phoenix",
pets: [],
},
{
name: "stephanie",
age: 27,
from: "Chicago",
pets: [{
type: "dog",
name: "midnight",
age: 3,
}, ],
},
{
name: "david p",
age: 40,
from: "Lancaster",
pets: [{
type: "dog",
name: "quinn",
age: 8,
}, ],
},
{
name: "patrick",
age: 39,
from: "Poway",
pets: [{
type: "dog",
name: "hazel",
age: 7,
},
{
type: "cat",
name: "fredy perlman",
age: 13,
},
],
},
{
name: "david a",
age: 32,
from: "San Francisco",
pets: [{
type: "monstera",
name: "holey",
age: 1,
}, ],
},
{
name: "timm",
age: 32,
from: "Gainsville",
pets: [{
type: "goldfish",
name: "betsy",
age: 4,
}, ],
},
{
name: "conrad",
age: 101,
from: "Minneapolis",
pets: [],
},
{
name: "nate",
age: 14,
from: "Boston",
pets: [{
type: "cat",
name: "rosie",
age: 0.005,
},
{
type: "hermit crab",
name: "kermit",
age: 1, // 16 wow wtf
},
{
type: "dog",
name: "ernie",
age: 4,
},
{
type: "cat",
name: "kendrick lamar jr",
age: 6,
},
{
type: "cat",
name: "guinan",
age: 589,
},
{
type: "cat",
name: "beverly",
age: 1,
},
],
},
{
name: "temo",
age: 25,
from: "Osaka",
pets: [{
type: "dog",
name: "nacho",
age: 1,
},
{
type: "dog",
name: "belky",
age: 1,
},
{
type: "dog",
name: "janeway",
age: 4,
},
{
type: "dog",
name: "jean-luc",
age: 12,
},
{
type: "monkey",
name: "shin chan",
age: 1,
},
],
},
{
name: "griffin",
age: 22,
from: "Chicago",
pets: [{
type: "bearded dragon",
name: "ferg",
age: 3,
}, ],
},
{
name: "eman",
age: 20,
from: "Lake in the Hills",
pets: [{
type: "parakeet",
name: "sunny",
age: 400,
},
{
type: "parrot",
name: "vic fontaine",
age: 46,
},
{
type: "parrot",
name: "worf",
age: 48,
},
{
type: "cockatoo",
name: "spockatoo",
age: 33,
},
],
},
{
name: "jürgen",
age: 28,
from: "Chicago",
pets: [{
type: "cat",
name: "mija",
age: 6,
}, ],
},
{
name: "michele",
age: 33,
from: "Rome",
pets: [{
type: "cat",
name: "caesar", // "cheeto"
age: 3,
},
{
type: "cat",
name: "cleopatra",
age: 3,
},
{
type: "cat",
name: "tuvok",
age: 10,
},
{
type: "turtle",
name: "spock",
age: 13,
},
],
},
{
name: "mitchell",
age: 19,
from: "Iowa City",
pets: [{
type: "cat",
name: "eddie",
age: 7,
}, ],
},
{
name: "reuben",
age: 41,
from: "Durham",
pets: [{
type: "cat",
name: "nico",
age: 15,
},
{
type: "cat",
name: "rocky",
age: 5,
},
],
},
{
name: "fatima",
age: 24,
from: "Milwaukee",
pets: [{
type: "snake",
name: "reginald",
age: 12,
}, ],
},
];
const totalAgeAllPets = data.reduce((result, pet) => {
return result pet.pets.reduce((a, p) => a p.age, 0);
}, 0);
console.log(totalAgeAllPets);uj5u.com熱心網友回復：
一種方法可以如下所示：
const data = [
{
"name": "mark",
"age": 27,
"from": "Chicago",
"pets": []
},
{
"name": "greg",
"age": 68,
"from": "Auburn",
"pets": [
{
"type": "rock",
"name": "herbert",
"age": 126003219
}
]
},
{
"name": "ken",
"age": 28,
"from": "Naperville",
"pets": [
{
"type": "cat",
"name": "colby",
"age": 1
},
{
"type": "dog",
"name": "charlie",
"age": 3
},
{
"type": "dog",
"name": "william riker",
"age": 1
},
{
"type": "dog",
"name": "thomas riker",
"age": 1
}
]
},
{
"name": "kristiana",
"age": 47,
"from": "Chicago",
"pets": []
},
{
"name": "bryan",
"age": 27,
"from": "Lincoln Park Zoo",
"pets": [
{
"type": "white tiger",
"name": "arthur",
"age": 3
},
{
"type": "silverback gorilla",
"name": "tommy",
"age": 4
},
{
"type": "guinea pig",
"name": "kirk",
"age": 1
},
{
"type": "hamster",
"name": "spock",
"age": 1
},
{
"type": "hamster",
"name": "sarek",
"age": 1
},
{
"type": "cat",
"name": "quark",
"age": 1
},
{
"type": "cat",
"name": "kira nerys",
"age": 1
}
]
},
{
"name": "anthony",
"age": 31,
"from": "Phoenix",
"pets": []
},
{
"name": "stephanie",
"age": 27,
"from": "Chicago",
"pets": [
{
"type": "dog",
"name": "midnight",
"age": 3
}
]
},
{
"name": "david p",
"age": 40,
"from": "Lancaster",
"pets": [
{
"type": "dog",
"name": "quinn",
"age": 8
}
]
},
{
"name": "patrick",
"age": 39,
"from": "Poway",
"pets": [
{
"type": "dog",
"name": "hazel",
"age": 7
},
{
"type": "cat",
"name": "fredy perlman",
"age": 13
}
]
},
{
"name": "david a",
"age": 32,
"from": "San Francisco",
"pets": [
{
"type": "monstera",
"name": "holey",
"age": 1
}
]
},
{
"name": "timm",
"age": 32,
"from": "Gainsville",
"pets": [
{
"type": "goldfish",
"name": "betsy",
"age": 4
}
]
},
{
"name": "conrad",
"age": 101,
"from": "Minneapolis",
"pets": []
},
{
"name": "nate",
"age": 14,
"from": "Boston",
"pets": [
{
"type": "cat",
"name": "rosie",
"age": 0.005
},
{
"type": "hermit crab",
"name": "kermit",
"age": 1
},
{
"type": "dog",
"name": "ernie",
"age": 4
},
{
"type": "cat",
"name": "kendrick lamar jr",
"age": 6
},
{
"type": "cat",
"name": "guinan",
"age": 589
},
{
"type": "cat",
"name": "beverly",
"age": 1
}
]
},
{
"name": "temo",
"age": 25,
"from": "Osaka",
"pets": [
{
"type": "dog",
"name": "nacho",
"age": 1
},
{
"type": "dog",
"name": "belky",
"age": 1
},
{
"type": "dog",
"name": "janeway",
"age": 4
},
{
"type": "dog",
"name": "jean-luc",
"age": 12
},
{
"type": "monkey",
"name": "shin chan",
"age": 1
}
]
},
{
"name": "griffin",
"age": 22,
"from": "Chicago",
"pets": [
{
"type": "bearded dragon",
"name": "ferg",
"age": 3
}
]
},
{
"name": "eman",
"age": 20,
"from": "Lake in the Hills",
"pets": [
{
"type": "parakeet",
"name": "sunny",
"age": 400
},
{
"type": "parrot",
"name": "vic fontaine",
"age": 46
},
{
"type": "parrot",
"name": "worf",
"age": 48
},
{
"type": "cockatoo",
"name": "spockatoo",
"age": 33
}
]
},
{
"name": "jürgen",
"age": 28,
"from": "Chicago",
"pets": [
{
"type": "cat",
"name": "mija",
"age": 6
}
]
},
{
"name": "michele",
"age": 33,
"from": "Rome",
"pets": [
{
"type": "cat",
"name": "caesar",
"age": 3
},
{
"type": "cat",
"name": "cleopatra",
"age": 3
},
{
"type": "cat",
"name": "tuvok",
"age": 10
},
{
"type": "turtle",
"name": "spock",
"age": 13
}
]
},
{
"name": "mitchell",
"age": 19,
"from": "Iowa City",
"pets": [
{
"type": "cat",
"name": "eddie",
"age": 7
}
]
},
{
"name": "reuben",
"age": 41,
"from": "Durham",
"pets": [
{
"type": "cat",
"name": "nico",
"age": 15
},
{
"type": "cat",
"name": "rocky",
"age": 5
}
]
},
{
"name": "fatima",
"age": 24,
"from": "Milwaukee",
"pets": [
{
"type": "snake",
"name": "reginald",
"age": 12
}
]
}
];
const totalAgeOfAllPets = data.reduce((acc, curr) => {
curr?.pets?.forEach(({age}) => {acc = acc age});
return acc;
}, 0);
console.log(`Total age of all pets : ${totalAgeOfAllPets}`);uj5u.com熱心網友回復：
使用.flatMap()過濾掉所有非業主：
data.flatMap(obj => obj.pets.length > 0 ? obj.pets : [])
你會得到一個pet物件陣列。接下來使用reduce來得到所有的總和pet.age
.reduce((sum, pet) => sum pet.age, 0);
const data =[{name:"mark",age:27,from:"Chicago",pets:[]},{name:"greg",age:68,from:"Auburn",pets:[{type:"rock",name:"herbert",age:126003219}]},{name:"ken",age:28,from:"Naperville",pets:[{type:"cat",name:"colby",age:1},{type:"dog",name:"charlie",age:3},{type:"dog",name:"william riker",age:1},{type:"dog",name:"thomas riker",age:1}],},{name:"kristiana",age:47,from:"Chicago",pets:[]},{name:"bryan",age:27,from:"Lincoln Park Zoo",pets:[{type:"white tiger",name:"arthur",age:3},{type:"silverback gorilla",name:"tommy",age:4},{type:"guinea pig",name:"kirk",age:1},{type:"hamster",name:"spock",age:1},{type:"hamster",name:"sarek",age:1},{type:"cat",name:"quark",age:1},{type:"cat",name:"kira nerys",age:1}]},{name:"anthony",age:31,from:"Phoenix",pets:[]},{name:"stephanie",age:27,from:"Chicago",pets:[{type:"dog",name:"midnight",age:3}]},{name:"david p",age:40,from:"Lancaster",pets:[{type:"dog",name:"quinn",age:8}]},{name:"patrick",age:39,from:"Poway",pets:[{type:"dog",name:"hazel",age:7},{type:"cat",name:"fredy perlman",age:13}]},{name:"david a",age:32,from:"San Francisco",pets:[{type:"monstera",name:"holey",age:1}]},{name:"timm",age:32,from:"Gainsville",pets:[{type:"goldfish",name:"betsy",age:4}]},{name:"conrad",age:101,from:"Minneapolis",pets:[]},{name:"nate",age:14,from:"Boston",pets:[{type:"cat",name:"rosie",age:0.005},{type:"hermit crab",name:"kermit",age:1},{type:"dog",name:"ernie",age:4},{type:"cat",name:"kendrick lamar jr",age:6},{type:"cat",name:"guinan",age:589},{type:"cat",name:"beverly",age:1}]},{name:"temo",age:25,from:"Osaka",pets:[{type:"dog",name:"nacho",age:1},{type:"dog",name:"belky",age:1},{type:"dog",name:"janeway",age:4},{type:"dog",name:"jean-luc",age:12},{type:"monkey",name:"shin chan",age:1}]},{name:"griffin",age:22,from:"Chicago",pets:[{type:"bearded dragon",name:"ferg",age:3}]},{name:"eman",age:20,from:"Lake in the Hills",pets:[{type:"parakeet",name:"sunny",age:400},{type:"parrot",name:"vic fontaine",age:46},{type:"parrot",name:"worf",age:48},{type:"cockatoo",name:"spockatoo",age:33}]},{name:"jürgen",age:28,from:"Chicago",pets:[{type:"cat",name:"mija",age:6}]},{name:"michele",age:33,from:"Rome",pets:[{type:"cat",name:"caesar",age:3},{type:"cat",name:"cleopatra",age:3},{type:"cat",name:"tuvok",age:10},{type:"turtle",name:"spock",age:13}]},{name:"mitchell",age:19,from:"Iowa City",pets:[{type:"cat",name:"eddie",age:7},]},{name:"reuben",age:41,from:"Durham",pets:[{type:"cat",name:"nico",age:15},{type:"cat",name:"rocky",age:5}]},{name:"fatima",age:24,from:"Milwaukee",pets:[{type:"snake",name:"reginald",age:12}]}];
const totalAgeAllPets = data.flatMap(obj => obj.pets.length > 0 ? obj.pets : []).reduce((sum, pet) => sum pet.age, 0);
console.log(totalAgeAllPets);uj5u.com熱心網友回復：
另一種，只有一行解決方案：
const age = data.flatMap((o) => o.pets).reduce((acc, o) => acc o.age, 0);
console.log(age) //126004497.005
轉載請註明出處，本文鏈接：https://www.uj5u.com/qita/381561.html
標籤：javascript 数组 目的 减少
上一篇：將鍵物件對陣列轉換為C#物件
下一篇：繼承的類；如何實施