var moment = require('moment')
a = moment("2017-05-16")
b = moment("2017-05-17")
c = moment("2017-05-17")We should always use moment(a).isBefore(b) instead of a < b. Not because the latter does not
work (both forms work!); but rather, we might be tempted to assume something like a == b or a === b
behaves similarly.