flatten a collection of objects

gistfile1.txt

test('map a collection into a new array', assert => {
  const expected = [ { a:1 }, { a: 1 } ]
  const input = [ [ { a: 1 }, { b: 1 } ], [ { a: 1, c: 1 } ] ]
  const actual = [].concat.apply([], input)
    .filter(e => e.hasOwnProperty('a'))
    .map(e => {
      return { a: e.a }
    })
  assert.deepEqual(actual, expected)
  assert.end()
})