alt Hacker News> Em-dashes are a lot more freeform and informal. They communicate a similar tone as when you're speaking and you suddenly stop to mention something that just occurred to you.
Isn't that supposed to be en-dash? I swear I remember em-dash being more restricted in use.
No, an en-dash is used for a range, like "5–10", or in talking about two things and their relationship, like Franco–Prussian War.