Why javascript is not well constructing my date

Question

In my Angular 6 project, I have the following code:

const date1 = new Date(2018, 9, 17);
console.log('date1 = ', date1);

But I get the following result in the cosole of my browser:

date1 =  Wed Oct 17 2018 00:00:00 GMT+0200 (Central European Summer Time)

Why do I get Oct but not Sept?

Answer 1

That is because

The argument monthIndex is 0-based. This means that January = 0 and December = 11.

For More: Date Parameters