TypeError: date[("get" + method)] is not a functio code example

Example: Uncaught TypeError: d[("get" + method)] is not a function

'start': moment(t.runAt), 'end': moment(t.runAt).add(30, 'minute')

to 

'start': moment(t.runAt).toDate(), 'end': moment(t.runAt).add(30, 'minute').toDate()