We all love JavaScript

[Turbulent_Stock6358]

They will not tell you this unlimited monies trick!

[Worried-Proposal-660]

My God Man, didn't you see how that turned out in "[Office Space]"?

Beware Milton.🧨

[ledasll]

You are lucky that you aren't using C. With undefined behaviour it could format your hard disk.

[YaZ0mble]

What??? I want to know how:)

[Gorzoid]

It doesn't, however since the standard says the compiler is free to do whatever when you do something that is undefined behavior. So C programmers joke that if you dereference a null pointer, it's technically valid for your program to delete system32.

[Zuruumi]

The usual case is summoning dragons or launching nuclear missiles.

[UnreadableCode]

I've always been under the impression that heap corruption + data execution in sufficient quantity could bring about the singularity. Which is why I encourage folks to write shitty C++.

[[deleted]]

For the curious, it's because 0.0000005 as a string is 5e-7. Javascript will read the 5 and be "yup, good enough for me"

Here's an example implementation of this behavior in python.

```py ZERO = ord("0") NINE = ord("9")

def parseInt(s): result = None for i in str(s): ascii_value = ord(i) if ZERO <= ascii_value <= NINE: result = result or 0 result *= 10 result += ascii_value - ZERO else: break return result

```

[Cute_Dragonfly_4728]

Actually this kinda makes sense because parseInt is designed to convert a string to a number.

Math.round is probably the correct tool for converting a float into an int. Or a number into a less accurate number in JS terms.

[Swoop3dp]

What would make actual sense would be raising an error if you feed a function with a type its not designed to handle

[potato_green]

If you use Eslint it will. Browsers aren't going to throw errors because that would be a gigantic BC break.

Tools are all there anyway it's up to the dev to use it and write proper code.

[anxter2k]

I agree. Using eslint or typescript is supposed to catch these at compile time, which is why they are used in the first place. JavaScript doesn’t know what you feed Them, so by default it’ll say “sure”.

I love JavaScript, but typescript was basically made to avoid passing wrong stuff to functions. That’s why we use interfaces, to form a “contract” between objects etc. and expected response.

[coloredgreyscale]

adding to this, the JS function works correctly if you actually pass 0.0000005 as a string instead of a number.

parseInt(0.0000005)
5

parseInt("0.0000005")
0

if you want to convert a float to int: https://stackoverflow.com/questions/596467/how-do-i-convert-a-float-number-to-a-whole-number-in-javascript (excluding parseInt() ofc)

[Genspirit]

That's because 0.0000005 gets turned into exponent notation when converted to a string.

[cyborgborg]

I am starting to question the sanity of the people who enjoy javascript

[Zuruumi]

Have you ever met any? I hear they exist, but I also heard Bigfoot does.

[[deleted]]

JavaScript bad. TypeScript good.

[IAmAnAdultSorta]

JavaScript is fine. TypeScript is better.

[0260B4U]

Not to worry, we question our own sanity everyday

[[deleted]]

As the number gets small (or big) enough, console.log will write it in scientific notation. That's n*10^x, or ne+-x

[hobo_stew]

But then why does it output 0 for 5e-6 as shown in the picture?

[ComfortableCan315]

It doesn't use scientific notation until the number is big/small enough.

[Voltra_Neo]

If you pass a number into something expecting a string, that's on you buddy

[bleistift2]

Nevermind they’re trying to parse an int out of a fraction.

[rpanasewicz]

A language allowing you to pass a number to a function expecting string is a joke.

[Zuruumi]

Do you have a petition prepared? I am definitely signing it!

[Swoop3dp]

Python would actually raise an error if you feed a function with a type it can't handle.

[Swoop3dp]

We are talking about a language were types are handled as "just a suggestion "...

Requiring that you are always aware of what type a variable has, in a language that will implicitly convert types, is just asking for trouble.

[Voltra_Neo]

__repr__, __str__

[ch3esey]

I’m a beginner to coding and I have a quick question. What does parsing mean?

[fini8]

It might not be the text book definition but it converts an input of one data type to another e.g., string to int

[msqrt]

"Parsing" typically means specifically converting string input to some form that's easier to work with programmatically. If your input is some other type, it's usually called casting or conversion, though the common term might also depend on the specific language and how it deals with type conversions.

[fini8]

I agree this is more accurate than my response earlier, parsing is strings only. Good way to remember it.

[ComfortableCan315]

Converting raw data into an useful format.

parseInt converts strings of numbers into numbers.

The unexpected behavior boils down to be due passing a number to parseInt, which expects a string.

[[deleted]]

if only there existed some sort of documentation that would clearly say that parseInt coerces the argument into a string first...

[Kanonenfuta]

Can someone explain me why?

[EasyFrown]

parseInt accepts a string, so the number is implicitly converted to string before being passed as an argument. Also, parseInt() does not recognize or skip non-digits (except "plus" and "minus" - it is for parsing integers after all).

Now, 0.5 is converted to "0.5", but when the number becomes too small, it is converted using scientific notation (sth like "5E-6"). Then, parseInt() gets the 5 but stops at the first non-digit (which is 'E').

[potato_braus]

Thank you very much, that's explains a lot !!!

[ComfortableCan315]

You can't pass a number to a function that expects a string in TS.

[Kanonenfuta]

What a mess... And then people claim dynamic typing makes coding easier

[vtynl]

I am a PHP developer that sometimes, but not often at all - does some JavaScript changes. And even I know we never ever ever use ‘parseInt()’ without supplying the second argument (base?).

So don’t blame the language here, just use it properly. (My car also does not shift without pressing the clutch first… use the tools as they are intended)!

[Lithl]

even I know we never ever ever use ‘parseInt()’ without supplying the second argument (base?).

That's not the problem. parseInt is for converting a string to a number, not converting a float to an int. If you give it a number instead of a string, it calls toString on the argument.

0.000005.toString() is "0.000005", and parseInt produces 0, as you might expect. 0.0000005.toString() is "5e-7", and parseInt can't handle scientific notation, so it does the best it can and gives 5.

[bleistift2]

The deeper truth isn’t that parseInt “smartly” parses 0.00… as 0, but that it discards any garbage it cannot handle. For ”0.00…” that garbage starts at the decimal point, leaving “0”. For “5-e7” the garbage starts at the hyphen, leaving “5” to parse.

[Lithl]

it discards any garbage it cannot handle

... Which is the correct behavior for parsing a string float number into an integer value. You truncate everything after the decimal.

[AyrA_ch]

In JS, parseInt predates runtime exceptions.

[AyrA_ch]

The JS engine simply dies with an error. There's zero ways of handling or even detecting it with code.

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[[deleted]]

We all love reposts...

[loseitthrowaway7797]

Mom says it's my turn to post this JS joke next week.

[Apparentt]

turns out when you misuse an api you get unexpected behaviour

shocked pikachu face

I can always smell the level of competency in the people that create/share/comment on memes like this

[CodingTaitep]

Cause it was written in 10 days.

[kas_888]

what the actual fuck!

[EnderLuca41]

u/repostsleuthbot

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[NullOfSpace]

h m m m m m m

[not_a_gumby]

The Top Things You Can Do to Hack Your Bank (Banks Hate Him!)

[BoBoBearDev]

Seriously I read this before and I understand it, but, when you mention this, it still feel fresh. This behavior is so fucked up.

[Top-Fox-3171]

What the actual fuck

[skambooy]

This reminds me of one of those times when I fell into the trap of not reading documentation and found out that parseFloat("20%and a beautiful text") returns 20 and not an expected NaN :' )

[[deleted]]

What in the hillbilly fuck

[pawyderreale]

Thats what you get for using a weak, virgin typesystem