Why don't you all just use === instead of ==?

Tell me, how long does it take to learn it?

The all these weird quirks thing was really a naive me talking back then. JS was my second language after Java. Anonymous functions, async execution, implicit typing, weak typing - it requires a different way of thinking when you move from Java to JS and you're just starting. Most everything is explicitly defined, and everything executes in the order that is listed in Java. JS is whole different beast.

I would never suggest people start learning programming with JS first... although, there is the huge benefit of not needing more than a text editor and browser (already on their machine) to get started with it. One area of JS that I HATE is Date... it sucks, it's woefully incomplete and moment-timezone is huge to download in a browser.

The primitives, coercion and a lot of other bits of JS I really appreciate... but === vs == is pretty low on my list... that said, I tend to prefer the airbnb eslint preset, so it makes me use it anyway.

FWIW, I've never used ==

I don't consider it a foresight issue. I'm a believer in putting the burden on the caller not the callee. If I expect 0 and you have "0", it's your job to call parseInt(), not my job to branch out some if statements for type checking and coercion. For a few reasons:

1) debugging someone else's code is a lot more time consuming than debugging your own

2) actually fixing a bug in someone else's code means a pull request to someone who may not actively maintain that code

3) the docs are simpler to write and easier to read.

It's my only pain point with the JS community. The "give me whatever and I'll see if I can handle it for you" mentality:

  function doStuff(a, b, c) {

      if (!c && b instanceof Function) {
          c = b;
      }
      c()
  }

I'd rather be expressly told what to give you than try to read a wall of if statements in both the docs and your code.

That said, the biggest problem I've seen in a lot of projects, bigger than coercion and in languages including, but not limited to JS is not properly handling error cases.

That's a HUGE problem. This is an absolutely fucking nightmare. It's arguably the hardest thing to possibly debug, because you're not informed it's a bug. No amount of error handling will solve that, which you've pointed out as "the biggest problem".

> If someone calls me with invalid input, and it's coerced and you get invalid output

But this isn't the problem. The problem is when it gets called with invalid input and somehow gets coerced into a valid but unexpected output. Expected input -> Expected output means you get instant gratification as to whether or not it works. This dramatically reduces the number of error cases which naturally and effortlessly moves toward solving your complaint.