how to solve the merge mysql tables to getting json data from express api to transform data into sutdent section id wise in JavaScript

Question

getting the response from express api how can change the array data like this thanks in advance help me !

input = [
    { secId: "12", stuName: "aaa", stuGrade: "A", stuTotal: 100 },
    { secId: "12", stuName: "bbb", stuGrade: "A+", stuTotal: 98 },
    { secId: "13", stuName: "ccc", stuGrade: "B", stuTotal: 95 },
    { secId: "13", stuName: "ddd", stuGrade: "A", stuTotal: 70 },
  ];

output = [
    {
      secId: 12,
      stuDetails: [
        { stuName: "aaa", stuGrade: "A", stuTotal: 100 },
        { stuName: "bbb", stuGrade: "A+", stuTotal: 98 },
      ],
    },
    {
      secId: 13,
      stuDetails: [
        { stuName: "ccc", stuGrade: "B", stuTotal: 95 },
        { stuName: "ddd", stuGrade: "A", stuTotal: 70 },
      ],
    },
  ];

Answer 1

We can do it via Array.reduce()

let input = [
    { secId: "12", stuName: "aaa", stuGrade: "A", stuTotal: 100 },
    { secId: "12", stuName: "bbb", stuGrade: "A+", stuTotal: 98 },
    { secId: "13", stuName: "ccc", stuGrade: "B", stuTotal: 95 },
    { secId: "13", stuName: "ddd", stuGrade: "A", stuTotal: 70 },
  ];
  
let output = input.reduce((a,v) => {
   let {secId,...item} = v
   let obj = a.find(i => i.secId === secId)
   if(obj){
     obj.stuDetails.push(item)
   }else{
     a.push({'secId':secId,'stuDetails':[item]})
   }
   return a
},[])
console.log(output)