CODE EXAMPLE FOR JAVASCRIPT

js two array combining with id neasted

const a1 = [{ id : 1, name : "test"}, { id : 2, name : "test2"}]
const a2 = [{ id : 1, count : "1"}, {id : 2, count : "2"}]

const merge = (arr1, arr2) => {
  const temp = []

  arr1.forEach(x => {
    arr2.forEach(y => {
      if (x.id === y.id) {
        temp.push({ ...x, ...y })
      }
    })
  })

  return temp
}

console.log(merge(a1, a2))