SOURCE

let chapterDetail=[
  {
  id:1961,
  introduction:"",
  name:"测试试卷勿动",
  paperChapterQuestion:[
      {
      id:40289,
      questionScore:20,
      question:{
        quesStem:"一年有几个节",
        quesType:1
        }
      },
      {
      id:40290,
      questionScore:30,
      question:{
        quesStem:"一年有多少天",
        quesType:2
        }
      },
      {
       id:40291,
       questionScore:40,
       question:{
         quesStem:"一年有12个月",
         quesType:3
        }
      },
      {
      id:40292,
      questionScore:10,
      question:{
       quesStem:"一年有多少节气",
       quesType:3
      }
    }
  ]
  }
]

chapterDetail.forEach(item=>{
   item.questionReqList = item.paperChapterQuestion.map(item1=>{
     return {
        ...item1,
        ...item1.question
     }
   })
})
console.log(chapterDetail)