POV: you don't understand type coercion
this post was submitted on 16 Jun 2023
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This one is one of my favourite JS quirks:
Wait wtf is happening there?
parseInt is meant for strings so it converts the number there into a string. Once the numbers get small enough it starts representing it with scientific notation. So 0.0000001 converts into "1e-7" where it then starts to ignore the e-7 part because that's not a valid int, so it is left with 1
https://javascript.plainenglish.io/why-parseint-0-0000001-0-8fe1aec15d8b
Ok some of these I understand but what the fuck. Why.
Edit: ok I have a theory. == checks equality without casting to any types, so they're not equal. But < and > are numeric operations, so null gets cast to 0. So <= and >= cast it to 0, and it's equal to 0, so it's true.
I'm not sure if you really want to know, but:
greater than, smaller than, will cast the type so it will be 0>0 which is false, ofcourse. 0>=0 is true.
Now == will first compare types, they are different types so it's false.
Also I'm a JavaScript Dev and if I ever see someone I work with use these kind of hacks I'm never working together with them again unless they apologize a lot and wash their dirty typing hands with.. acid? :-)
edit: as several people already pointed out, my answer is not accurate. The real solution was mentioned by mycus
Can someone explain this? I mean, the last result. Usually I can at least understand Javascript's or PHP's quirks. But this time I'm stumped.
JS null and undefined shenanigans
basically:
- bigger an lesser comparison types convert null to zero, so is zero bigger or lesser than zero? no
==is fucky and to it null only equals undefined and undefined only equals null (and themselves), so no- is zero bigger than or equal to zero? yeah
Ugh, thanks, of course. Stupid brain.
I'm starting to think JS maintainers have a thing against mathematicians
more likely against humans
I know it’s a joke, but it’s an old one and it doesn’t make a lot of sense in this day and age.
Why are you comparing null to numbers? Shouldn’t you be assuring your values are valid first? Why are you using the “cast everything to the type you see fit and compare” operator?
Other languages would simply fail. Once more JavaScript greatest sin is not throwing an exception when you ask it to do things that don’t make sense.
Shouldn’t you be assuring your values are valid first?
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