const diff = require('diff-arrays-of-objects');
var result = diff(
  [
    {id: 1, name: 'a'},
    {id: 2, name: 'b'},
    {id: 3, name: 'c'},
    {id: 4, name: 'd'},
    {id: 5, name: 'e'}
  ],
  [
    {id: 1, name: 'a'},
    {id: 2, name: 'z'},
    {id: 7, name: 'e'}
  ],
  'id'
);

console.log(result)
// {
//   added: [
//     { id: 7, name: 'e' }
//   ],
//   removed: [
//     { id: 3, name: 'c' },
//     { id: 4, name: 'd' },
//     { id: 5, name: 'e' }
//   ],
//   updated: [
//     { id: 2, name: 'z' }
//   ],
//   same: [
//     { id: 1, name: 'a' }
//   ]
// }

{
  compareFunction: <Func> // defaults to lodash's isEqual; must accept two parameters (o1, o2)
  updatedValues: <Number> // controls what gets returned in the "updated" results array:
                          // diff.updatedValues.first (1): the value from the first array
                          // diff.updatedValues.second (2): the value from the second array (default)
                          // diff.updatedValues.both (3): both values, as an array [first, second]
                          // diff.updatedValues.bothWithDeepDiff (4): both values, plus the results of the deep-diff module; [first, second, deep-diff]
}

const diff = require('diff-arrays-of-objects');
const first = [{ id: 1, letter: 'a' }];
const second = [{ id: 1, letter: 'b' }];

const result = diff (first, second, idField, { updatedValues: diff.updatedValues.first });
// result.updated is [{ id: 1, letter: 'a' }]

const result = diff (first, second, idField, { updatedValues: diff.updatedValues.second });
// result.updated is [{ id: 1, letter: 'b' }]

const result = diff (first, second, idField, { updatedValues: diff.updatedValues.both });
// result.updated is [{ id: 1, letter: 'a' }, { id: 1, letter: 'b' }]

const result = diff (first, second, idField, { updatedValues: diff.updatedValues.bothWithDeepDiff });
// result.updated is [{ id: 1, letter: 'a' }, { id: 1, letter: 'b' }, { kind: 'E', path: ['letter'], lhs: 'a', rhs: 'b' }]