[Karunamon]

I assume you're referring to the "Wat" talk by Gary Bernhardt, here.

My question is why does it matter? It's funny and notable behavior, but why is this a problem that a real programmer will face dealing with a real problem?

(For reference, [] + [] = "", [] + {} = Object, {} + [] = 0, {} + {} = NaN)

[marcosdumay]

It matters because it shows how incoherent is the Javascript type system, and how easy it is to get biten by it.

About Python lambdas, I miss them a lot. But one can not have everything...

[rdtsc]

Because it hides errors instead of helping the developer find them

[Karunamon]

Are JS developers often adding empty arrays and empty objects together? This seems more like a corner case than a real issue.

(Not snarky - I don't know JS)

[rdtsc]

As often as any programmers deliberately insert bugs in their code ;-)

Those values are usually in variables that and have been set maybe from a backend reply or from the UI at some point.

That is just one instance of the sloppy mess of weak typing. Instead of writing a long list of it I just used an example to illustrate.

[tokenizerrr]

No. You generally only add numbers and strings together.

[gtirloni]

Extreme nonsense behavior from the language you're using. People see that and think "that's just the tip of the iceberg".