[英]Spread syntax for nested javascript object with dynamic properties for grouping
const data = [{year:2019,month:1,id:"xd1"},
{year:2019,month:1,id:"xd2"},
{year:2019,month:1,id:"xd4"},
{year:2019,month:2,id:"xd1"},
{year:2018,month:1,id:"rd3"},
{year:2018,month:2,id:"rd6"},
{year:2018,month:2,id:"rd7"}
]
const result = data.reduce((state,d)=>{
return {
...state,
[d.year]:{
...state[d.year],
[d.month]:[
...state[d.year][d.month]
,d.id]
}
}
},{})
console.log(result);
const result = data.reduce((state,d)=>{
return {
...state,
[d.year]:{
...state[d.year],
[d.month]:[].concat([state[d.year][d.month]],[d.id])
}
}
},{})
both return an Error TypeError: Cannot read property '1' of undefined
How can I use the spread syntax to get a grouped result like this. 都返回错误TypeError: Cannot read property '1' of undefined
如何使用扩展语法获取这样的分组结果。
{'2019':{
'1':["xd1","xd2","xd3"],
'2':["xd1"]},
'2018':{
'1':["rd3"],
'2':["rd6","rd7"]
}
}
Please consider using reduce and spread syntax and not chaining other methods because the its actually part of a bigger construct and other things wont help. 请考虑使用reduce和spread语法,而不要链接其他方法,因为它实际上是较大结构的一部分,其他方面无济于事。 Thx. 谢谢。 EDIT: like stated in the comments. 编辑:如评论中所述。 I would explicitly like solve it inline with spread operator that returns new objects or arrays. 我想明确地使用传播运算符来内联解决它,该运算符返回新的对象或数组。 No extra libraries like lodash. 没有像lodash这样的额外库。
Just add some sh*t and sticks
: 只需添加一些sh*t and sticks
:
const data = [{year:2019,month:1,id:"xd1"}, {year:2019,month:1,id:"xd2"}, {year:2019,month:1,id:"xd4"}, {year:2019,month:2,id:"xd1"}, {year:2018,month:1,id:"rd3"}, {year:2018,month:2,id:"rd6"}, {year:2018,month:2,id:"rd7"} ] const result = data.reduce((state, d) => { return { ...state, [d.year]: { ...state[d.year], [d.month]: [ ...((state[d.year]||{})[d.month]||[]), d.id] } } },{}) console.log(result);
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