两个数组和1个对象合并成一个数组对象的排列组合

const userIds = [1, 2]
const dates = ["2021-01-09", "2021-01-10"]
const obj = {
"time_from": "09:00:00",
"time_to": "20:00:00",
"rest_hours": 1
}
最终结果
[{
"user_id": 1,
"date":"2021-01-09"
"time_from": "09:00:00",
"time_to": "20:00:00",
"rest_hours": 1
},{
"user_id": 1,
"date":"2021-01-10"
"time_from": "09:00:00",
"time_to": "20:00:00",
"rest_hours": 1
},{
"user_id": 2,
"date":"2021-01-09"
"time_from": "09:00:00",
"time_to": "20:00:00",
"rest_hours": 1
},{
"user_id": 2,
"date":"2021-01-10"
"time_from": "09:00:00",
"time_to": "20:00:00",
"rest_hours": 1
}]

回答

var userIds = [1, 2]
var dates = ["2021-01-09", "2021-01-10"]
var obj = {
  "time_from": "09:00:00",
  "time_to": "20:00:00",
  "rest_hours": 1
}
userIds.map(user=>{
    return dates.map(date=>{
        return Object.assign({
            user_id: user,
            date: date,
        },obj)
    })
}).flat()

var userIds = [1, 2]
var dates = ["2021-01-09", "2021-01-10"]
var obj = {
  "time_from": "09:00:00",
  "time_to": "20:00:00",
  "rest_hours": 1
}
userIds.map(user=>{
    return dates.map(date=>{
        return Object.assign({
            user_id: user,
            date: date,
        },obj)
    })
}).flat()