why I get display next month instead of current month

Question

Why I see this page is in wrong month, it should init to show August instead of September , I am from cambodia

http://react-day-picker.js.org/examples/months-initial

Answer 1

From MDN docs: The argument month is 0-based. This means that January = 0 and December = 11.

var startOfYear =  new Date(2017,0)
console.log(startOfYear.toLocaleString())

Reference: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date