映射/挖掘嵌套在对象中的数组 - JavaScript
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【中文标题】映射/挖掘嵌套在对象中的数组 - JavaScript【英文标题】：Mapping/digging into an array that is nested in an object - JavaScript 【发布时间】：2021-10-20 18:50:33 【问题描述】：这是我关于堆栈溢出的第一个问题。我正在尝试映射一个位于对象内的数组。我的问题更多是关于定位而不是实际的映射过程本身（我认为）。我的代码的目标是将一个数组映射到这个目标：
var target =
"id": 1, //as an int
"type": "donut",
"name": "Cake",
"ppu": 0.55,
"batters": "all of the batter types as a string",
"ingredients": [],//a copy of all the toppings
"countOfFillings": 0
有问题的对象是：
var bakery =
"items":
"item":
[
"id": "0001",
"type": "donut",
"name": "Cake",
"ppu": 0.55,
"batters":
"batter":
[
"id": "1001", "type": "Regular" ,
"id": "1002", "type": "Chocolate" ,
"id": "1003", "type": "Blueberry" ,
"id": "1004", "type": "Devil's Food"
]
,
"topping":
[
"id": "5001", "type": "None" ,
"id": "5002", "type": "Glazed" ,
"id": "5005", "type": "Sugar" ,
"id": "5007", "type": "Powdered Sugar" ,
"id": "5006", "type": "Chocolate with Sprinkles" ,
"id": "5003", "type": "Chocolate" ,
"id": "5004", "type": "Maple"
]
,
"id": "0002",
"type": "donut",
"name": "Raised",
"ppu": 0.55,
"batters":
"batter":
[
"id": "1001", "type": "Regular"
]
,
"topping":
[
"id": "5001", "type": "None" ,
"id": "5002", "type": "Glazed" ,
"id": "5005", "type": "Sugar" ,
"id": "5003", "type": "Chocolate" ,
"id": "5004", "type": "Maple"
]
,
"id": "0003",
"type": "donut",
"name": "Old Fashioned",
"ppu": 0.55,
"batters":
"batter":
[
"id": "1001", "type": "Regular" ,
"id": "1002", "type": "Chocolate"
]
,
"topping":
[
"id": "5001", "type": "None" ,
"id": "5002", "type": "Glazed" ,
"id": "5003", "type": "Chocolate" ,
"id": "5004", "type": "Maple"
]
,
"id": "0004",
"type": "bar",
"name": "Bar",
"ppu": 0.75,
"batters":
"batter":
[
"id": "1001", "type": "Regular" ,
]
,
"topping":
[
"id": "5003", "type": "Chocolate" ,
"id": "5004", "type": "Maple"
],
"fillings":
"filling":
[
"id": "7001", "name": "None", "addcost": 0 ,
"id": "7002", "name": "Custard", "addcost": 0.25 ,
"id": "7003", "name": "Whipped Cream", "addcost": 0.25
]
,
"id": "0005",
"type": "twist",
"name": "Twist",
"ppu": 0.65,
"batters":
"batter":
[
"id": "1001", "type": "Regular" ,
]
,
"topping":
[
"id": "5002", "type": "Glazed" ,
"id": "5005", "type": "Sugar" ,
]
,
"id": "0006",
"type": "filled",
"name": "Filled",
"ppu": 0.75,
"batters":
"batter":
[
"id": "1001", "type": "Regular" ,
]
,
"topping":
[
"id": "5002", "type": "Glazed" ,
"id": "5007", "type": "Powdered Sugar" ,
"id": "5003", "type": "Chocolate" ,
"id": "5004", "type": "Maple"
],
"fillings":
"filling":
[
"id": "7002", "name": "Custard", "addcost": 0 ,
"id": "7003", "name": "Whipped Cream", "addcost": 0 ,
"id": "7004", "name": "Strawberry Jelly", "addcost": 0 ,
"id": "7005", "name": "Rasberry Jelly", "addcost": 0
]
]
var exampleTest = bakery.items.item.map(mapCake);
function mapCake (aCake)
let newType = `$bakery.items.item[1].type`
let result = id: `$bakery.items.item[0].id`,
type: newType,
name: `$bakery.items.item[0].name`,
ppu: `$bakery.items.item[0].ppu`,
batters: [`$bakery.items.item[0].batters.batter`],
ingredients: `$bakery.items.item[0].topping`,
countOfFillings: `$bakery.items.item[0].fillings`.length;
return result
【问题讨论】：
【参考方案1】：试试这个：
function mapCake(aCake)
let newType = `$aCake.type`;
let result =
id: `$aCake.id`,
type: newType,
name: `$aCake.name`,
ppu: `$aCake.ppu`,
batters: [`$aCake.batters.batter`],
ingredients: `$aCake.topping`,
countOfFillings: `$aCake.fillings`.length
;
return result;
看起来在你的函数中你每次都直接索引一个特定的面包店项目。
您的 aCake 参数尚未被使用，在每次迭代中，aCake 指的是正在迭代的当前项目 - 所以这就是您要填充结果值的内容。
【讨论】：
非常感谢您的帮助。这就说得通了。如果你不使用它，为什么要有一个参数。再次感谢您的宝贵时间！以上是关于映射/挖掘嵌套在对象中的数组 - JavaScript的主要内容，如果未能解决你的问题，请参考以下文章