向子对象追加父键

Question

我有以下对象给定:

{
"groupA": [
{data: 'foo'},
{data: 'bar'}
],
"groupB": [
{data: 'hi'},
{data: 'mom'}
]
}

我想把父对象键附加到它的所有数组项，像这样:

{
"groupA": [
{data: 'foo', set: 'groupA'},
{data: 'bar', set: 'groupA'}
],
"groupB": [
{data: 'hi', set: 'groupB'},
{data: 'mom', set: 'groupB'}
]
}

我怎样才能做到这一点?

Answer 1

这是一个不可变的版本，使用Object.fromEntries、Object.entries和map给你一个新的对象

const data = {
"groupA": [{
data: 'foo'
},
{
data: 'bar'
}
],
"groupB": [{
data: 'hi'
},
{
data: 'mom'
}
]
}
const withGroup = Object.fromEntries(
Object.entries(data).map(([set, items]) => [set, items.map(i => ({ ...i,set}))])
)
console.log(withGroup)

Answer 2

您可以循环设置每个条目

const obj = {
"groupA": [
{data: 'foo'},
{data: 'bar'}
],
"groupB": [
{data: 'hi'},
{data: 'mom'}
]
};
Object.entries(obj).forEach(([key,val]) => val.forEach(item => item.set=key))
console.log(obj)

Answer 3

您可以通过循环遍历对象并映射数组来实现，如下所示:

const data = {
"groupA": [
{data: 'foo'},
{data: 'bar'}
],
"groupB": [
{data: 'hi'},
{data: 'mom'}
]
};
Object.keys(data).forEach(key => {
data[key] = data[key].map(rec => ({...rec, set: key}));
})
console.log(data);

Answer 4

您也可以使用for...in

let data = {
"groupA": [
{data: 'foo'},
{data: 'bar'}
],
"groupB": [
{data: 'hi'},
{data: 'mom'}
]
}
for (const key in data) {
data[key] = data[key].map(item => ({...item, set: key}))
}
console.log(data);

Answer 5

您可以尝试Object.keys(arr)获取所有密钥名称:

let before = {
"groupA": [
{data: 'foo'},
{data: 'bar'}
],
"groupB": [
{data: 'hi'},
{data: 'mom'}
]
}
let after = {}
Object.keys(before).map((key) => {
let data = before[key].map((x) => { 
x.set = key
return x
})
after[key] = data 
})
console.log(before)
console.log(after)

==========

(更新)创建after，不修改before。

let before = {
"groupA": [
{data: 'foo'},
{data: 'bar'}
],
"groupB": [
{data: 'hi'},
{data: 'mom'}
]
}
let after = {}
Object.entries(before).forEach(([key, data]) => {
after[key] = data.map((before_value) => { 
return { 
...before_value, 
set: key
}
})
})
console.log(before)
console.log(after)