// Input
const dataSource = [
  {id: 48, code: "firstName",  description: "John"},
  {id: 49, code: "lastName",  description: "Smith"},
  {id: 49, code: "occupation",  description: "Agent"},
  {id: 47, code: "status",  description: "Active"},
]

// Output should be as follows
const output = {
  firstName: "John",
  lastName: "Smith",
  occupation: "Agent",
  status: "Active",
}

// Solution
const final = dataSource.reduce((accumulator, currentObj) => {
  const newObj = {};
  newObj[currentObj['code']] = currentObj['description'];
  return Object.assign(accumulator, newObj);
}, {})

console.log(final)