How to merge three different arrays by comparing with id? in Angular 6

Question

Arrays:

 array1 = [{id:1, name:"raju"},{id:2, name:"ravi"},{id:4, name:"john"},{id:6, name:"jack"}];
 array2= [{id:1, degree:"b.com"},{id:3, degree:"b.a"},{id:4, degree:"c.a"},{id:5, degree:"horticulture"}];
 array3= [{id:1, age:20},{id:3, age:21},{id:6, age:27},{id:7, age:25}];

Required result is:

resultarray = [
    {id:1, name: "raju", degree:"b.com",age:20},
    {id:2, name: "ravi"},
    {id:3, degree:"b.a", age:21},
    {id:4, name:"john", degree:"c.a"},
    {id:5, degree:"horticulture"},
    {id:6, name:"jack", age:27},
    {id:7, age:25}
 ] 

i have tried different functions and tried for two arrays but not able to merge the object which doesnt have id to compare..

Answer 1

You can use reduce and destructuring

Here idea is

• First merge all the arrays in one array.
• Now using reduce we create id as key in op object
• If id key is already there we merge the inp and op[inp.id]
• If id is not there we create a new key with value inp

let array1 = [{id:1, name:"raju"},{id:2, name:"ravi"},{id:4, name:"john"},{id:6, name:"jack"}];
let array2= [{id:1, degree:"b.com"},{id:3, degree:"b.a"},{id:4, degree:"c.a"},{id:5, degree:"horticulture"}];
let array3= [{id:1, age:20},{id:3, age:21},{id:6, age:27},{id:7, age:25}];

let temp = [...array1,...array2,...array3]

let op = temp.reduce((op,inp)=>{
  op[inp.id] = op[inp.id] || inp
  op[inp.id] = {...op[inp.id],...inp}
  return op
},{})

console.log(Object.values(op))

Answer 2

a possible solution:

let array1 = [{id:1, name:"raju"},{id:2, name:"ravi"},{id:4, name:"john"},{id:6, name:"jack"}];
let array2= [{id:1, degree:"b.com"},{id:3, degree:"b.a"},{id:4, degree:"c.a"},{id:5, degree:"horticulture"}];
let array3= [{id:1, age:20},{id:3, age:21},{id:6, age:27},{id:7, age:25}];

let resp = [].concat(array1, array2, array3).reduce((acc, ele) => {
        let obj = acc.find(x => x.id === ele.id);
        return obj ? (Object.keys(ele).forEach(x => obj[x] = ele[x]), acc) : acc.concat(ele);
    }, [])
    
console.log(resp)