keyboard – How to type a long / em dash `-`

When I write emails and articles, I often have to use a long dash - character not to be confused with the hyphen - character. Normally, what I end up doing is that I type two consecutive union strokes - and hit the Space key, which ends up replacing the two hyphens with the long dash.

However, when publishing articles in browser-based editors, this does not always work – as with the publisher's publication here – so I have to type the double dash of union + Space elsewhere, as in a fake email, copy the long dash from there and paste it here. It's very annoying of course.

I would like a shortcut to enter the long dash character directly.