ExFAANG Engineer Watches ExFAANG Take JavaScript Quiz | Prime Reacts
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- เผยแพร่เมื่อ 2 เม.ย. 2024
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Reviewed video: • ex-FAANG Developer vs ...
By: / @connerardman
/ theprimeagen
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I love that I have pretty much 0 experience with JS, and yet I can get every single question right by asking myself “what would be the craziest possible result here?”
Yeah they should've thrown some normal curve ball questions, so people don't automatically default to answer with the craziest possible choices.
This exactly happened to me as well
Except they did.. there were some normal expected ones there.@@kiattim2100
Just like in high-school, hahha...
javascript feels like when i try to interpret my dreams
And it works, but in mysterious ways.
Javascript was a mistake.
This joke made me crack a rib.
Profile picture checks out.
“I am currently a FAANG developer at this moment” - this was foreshadowing
It is truly amazing how much of JavaScript you miss out on by not doing aggressively stupid things with it
100% this
Yeah, I love how people who go on endlessly about weird JS auto-casting decisions. Why are you relying on automatic casting, then? It's a "problem" you inflict on yourself by not explicitly casting things.
I just gave this comment its 70th like. Sorry about that.
@@RichardRemer The largest problem is the same issue I have with PHP not running in strict mode. Even if I'm coding in TypeScript, at runtime an API could return the wrong type! It's a philosophy decision. JavaScript and PHP are deliberately designed to continue execution with garbage data rather than fail.
If your code does not look like
var myInt = new Array(0b17 % spaghetti*4);
... you are not really coding
The interview: "Invalid octal 018 that defaults to decimal minus valid octal 015"
The job: "Should I try to add this through more polymorphism or slap a Visitor pattern into all these classes?"
Uncaught SyntaxError: Octal literals are not allowed in strict mode.
@@fredoverflow hello this is CORS and fuck your app and especially those octal craps, I don't like them
perfect profile pic for this comment btw
When you can go Visitor, always go Visitor
In a javascript quiz the answer is always "why"
I find that applies more to languages like rust where everything is “ugh” and “why” and “do I really have to do all this and write macros for something that would be 1 line in c# or js”.
(Sorry, just learning rust and not having a great time. JavaScript looks pretty nice right now)
quiz is the answer. why is the question
@@svenmify rust is comparatively low level than c# or js. That's why.
@@testacals oh I know that. But something like Swift is also lower level (arguably a little less than rust), but way easier to code in.
A lot of the stuff I dislike about rust are design decisions
I finally understand the rust people.
Its javascipt devs who got out of a toxic relationship and now they want to date the opposite person.
The borrow checker might be annoying, but have you ever programmed in Javascript? - Rust devs
And after dating their opposite, theyll balance out in the middle, Go.
Or they take another detour and go elixir for a year
It's more like they have pathological tendencies and can't avoid toxic relationships, they went from idealizing JS to idealizing Rust.
Nah most of them go TS. Once they dip into the crazy they're hooked for life.
Funnily enough, I really like both JavaScript and Rust.
They complete each other.
For the Raw string question, in Python, we often use raw strings to type regex. They are already complicated enough, and we don't want to make them even more complicated by having to escape all the backslashes
It's also much nicer in Python because you just have to prepend an 'r' and you're good
And in Python you have to prepend 'f' to get variable formatting inside the string. (which you can combine with 'r' to get that French strings 🥖)
*python2 flashbacks*
Sounds like a skill issue. Real programmers escape all the backslashes and charge their employers for the time spent doing it. ;)
Same main reason why String.raw was introduced in JS; to be used to create regex patterns as strings that can be compiled to RegEx objects later that can be processed. Before this you'd have to escape the escapes, e.g. /Hello
World/ into `Hello\
\
World`.
Alternative title: "When you create a language over a weekend"
10 days actually
@@fredoverflow 🤓
It must be fun living in Prime's house hearing the muffled screams of "I KNEW IT" coming from his room throughout the house.
Hey man, just wanted to thank you.
I'm learning to code and despite working in tech for over a decade, there's a part of me that has always resisted/dreaded coding because in my mind it has always seemed like the epitome of postmodern desk slavery.
But you make it fun. You're always super hyped and having fun with coding. I'm not really learning that much from you, but listening to you having so much fun with it just makes it seem less soul sucking and has helped me have more positive associations with coding, which has really motivated me to do more learning in my spare time.
Just a fellow anon or here appreciating your passion. Never change!
This is really interesting to me.
Since in my mind code was always the thing that lets me make the computer do things.
Like, it's the stuff that video games are made out of and the fact that I know how to do that now would probably make 5 year old me happy. (and also makes me happy now :) )
@@cameron7374 yeah I'm coming to see it more like this now, largely thanks to prime and LLL.
It's weird - I had his experience with manufacturing first. When I started working with startups and got to see how things are made behind the scenes, actually going to suppliers, operating high tech machinery, working with vacuum chambers and plasma and lasers and CNC machines etc, it gave me a massive appreciation for the whole process. I was instantly hooked.
But software always seemed like the drab side of things. Working with hardware was interesting and seemed like it had more room for creativity; coding just seemed laborious, just stitching together the hardware with boring 1s and 0s.
It took actually taking a coding class and building some CLI apps in C to give me that same feeling about code. I see now how much of a rush it can be to problem solve with code, how intellectually stimulating it can be, and above all else how rewarding it is to build something that really works.
I'm taking a break from studying at the moment because my daughter was just born a few months ago, but watching prime and keeping up my practice on sololearn has me excited to get back to my comp eng classes.
I am pretty sure the title changed from “FAANG engineer reacts to ExFAANG engineer” right after the announcement on the main channel lol
I love this one even more:
String('123') instanceof String
JS is truly a language of all time
Pure rage.... But also, you construct new String objects with `new String()` and the fact that it doesn't crash when you do that without new is the part that's actually weird and wrong
@@itsteelworksof course. String is a function that converts things to primitive strings, and new String is a constructor that creates String instances.
You can even do this with your own types, just check new.target in your functions or constructors and return a value to use instead! Just remember that you can't return a primitive if the caller used new, or it will ignore the value and return the this value it created for you.
It's so simple and nice! 🫠
But Object('123') instanceof String is true
same for new Object()
Javascript, I love it
This is really easy to understand behavior though. It's quite consistent. Without "new", the function acts as a cast; with "new" it acts as a constructor.
I think the real problem lies in developers who are sloppy with their "new"s, and the many dual-purpose constructor/factories that accommodate them.
lol he updated the title cause he left Netflix 😂
I don't know about Javascript, but in other languages, the main use cases I've seen for raw strings are:
1. Writing regexes without having to escape \
2. Pasting the contents of a multi-line text file into a string literal.
3. Writing GLSL shaders or other dynamically compiled code from a different language, so they don't need to be shipped as separate files.
4. Writing multi-line strings for whatever other reason.
I love that you would never actually run into these problems if you code properly
It cares more about debugging and foundational understanding than pure DS&A.
I have to admit, against my better judgment, I like this quiz.
I'll have to lay down after this
Can’t tell if I’m being gaslit or if I have been saying NaN wrong all this time…. 😅
I mean, there are multiple ways of saying it.
“Nan”, “N A N” or “Not a number”.
Just like SQL.
“S Q L” or “Sequel”.
If you grew up with a typewriter (before eg graduating to a Vic20), the newline+return sequence makes perfect sense as they were two very distinct actions. 😂
Greatly enjoyed this episode.
Hearing expert JavaScript developers talk about its type system is a prime example of Stockholm Syndrome.
""""" type system """""
I'm going thru like a worst phase of my life! Both professionally ans personally.
Watching your videos makes my day. Thanks Prime.
JS's type coercion is a crime against humanity. Most of these questions should just TypeError…
You gotta remember the context. All the type casting is designed to interact with HTML form data. These values can only be strings. Brendan Eich's original design actually works very well in this context.
If you're not working with HTML forms, then why are you relying on type coercion? Cast explicitly and there are no issues.
Very interesting video, I got almost all of them wrong, except for the String.raw
I've had to use String.raw before when parsing JSON where some of the object attributes are also JSON (doubly stringified!), to avoid the backslashes in the double stringified json being used as escape characters
This is why I love the ThePrimagen: he turned an 11 minutes video into a 30 minute reaction. He's not just sitting there in the corner; he actually adds to the content. Love it.
I love that after 20min of bamboozling there was a phrase in an explanation to one of the questions: “if you do this instead you’d get a result you would have expected from the beginning”. You can’t expect anything after that
"If it's true, I'm gonna commit sudoku". Wow that's some high level of devotion to the cause man! :D
From the ECMAScript spec:
7.2.14 IsLooselyEqual ( x, y )
The abstract operation IsLooselyEqual takes arguments x (an ECMAScript language value) and y (an ECMAScript language value) and returns either a normal completion containing a Boolean or a throw completion. It provides the semantics for the == operator. It performs the following steps when called:
1. If Type(x) is Type(y), then
a. Return IsStrictlyEqual(x, y).
2. If x is null and y is undefined, return true.
3. If x is undefined and y is null, return true.
4. NOTE: This step is replaced in section B.3.6.2.
5. If x is a Number and y is a String, return ! IsLooselyEqual(x, ! ToNumber(y)).
6. If x is a String and y is a Number, return ! IsLooselyEqual(! ToNumber(x), y).
7. If x is a BigInt and y is a String, then
a. Let n be StringToBigInt(y).
b. If n is undefined, return false.
c. Return ! IsLooselyEqual(x, n).
8. If x is a String and y is a BigInt, return ! IsLooselyEqual(y, x).
9. If x is a Boolean, return ! IsLooselyEqual(! ToNumber(x), y).
10. If y is a Boolean, return ! IsLooselyEqual(x, ! ToNumber(y)).
11. If x is either a String, a Number, a BigInt, or a Symbol and y is an Object, return ! IsLooselyEqual(x, ? ToPrimitive(y)).
12. If x is an Object and y is either a String, a Number, a BigInt, or a Symbol, return ! IsLooselyEqual(? ToPrimitive(x), y).
13. If x is a BigInt and y is a Number, or if x is a Number and y is a BigInt, then
a. If x is not finite or y is not finite, return false.
b. If ℝ(x) = ℝ(y), return true; otherwise return false.
14. Return false.
ℝ(x) stands for the mathematical value of x, which normalizes +0 and -0 into 0 and is not defined for non finite values.
4. NOTE: This step is replaced in section B.3.6.2.
EXCUSE ME?
~26:40 - The rule is not completely consistent, at least not at first glance. Java uses a String pool for optimization and Strings that are referenced multiple times are therefore the same instance and `==` returns true. However that is not the case for all methods that can create new Strings. I do not know which methods create separate instances and which do not
It also differs based on JVM implementations, such as OpenJ9 having stricter string interning. You should definitely always use `.equals` when comparing strings, it short-circuit checks refs in the equals implementation anyway!
Besides regex, raw strings can also be for windows paths.
21:50 In the case that you're saying you don't know how to use it because you don't understand it, since it's raw but not really because it still evaluates the variables, the best way I can explain it is that that's only due to the backticks (``) surrounding the text, which I assume tells Javascript to evaluate the variables, and String.raw doesn't really interfere with this process. If it had the single or double quotes, it would have included the ${varOne} and ${varTwo}.
And in the other case where you are wondering why you would need to use String.raw at all, I have found myself needing to use this at times when I was trying to either be able to log out the raw thing in LLM responses, since I was trying to figure out if it was giving
or
alone. I bet there's some dynamic finetuning data generation use cases too.
String.raw can be used to get syntax highlighting for the code inside a string, for example, make a function named "yaml" and just return String.raw from it, call the function somewhere, write some yaml inside the backticks and you get yaml syntax highlighting, at least if you use neovim with treesitter.
i use js for all kinds of things, including scripting serial ports.
And i've used the string constructor to ensure proper type conversion in mozilla rhino
Non-FAANG Engineer Watches FAANG Engineer watching ExFAANG Engineer take JavaScript Quiz
24:26 YES, I have used the String constructor for an actual functioning purpose.
When you use the strings as map keys and two of those keys might be identical strings BUT you want to process the identical strings differently (for instance, based on their position or based on a user-selected process), then if you map the strings to their processing outputs, using String constructors lets you map two identical strings to two different processing outputs. If you didn't use the constructor, the second string processed would overwrite the first when you map that process output to the string, which you don't want if your goal is to process the two strings differently.
The catch is that you have to handle all keys symbolically or retrieve them with a keys() function call if you want them, which is fine since you're probably going to be processing dynamic instead of literal strings anyway.
Now, here's a bonus JavaScript quirk in the form of a quiz problem:
let a = new String('hey');
let b = new String('hey');
let c = 'hey';
console.log(a == c); // guess the output of this first, then try it
console.log(b == c); // guess the output of this second, then try it
console.log(a == b); // guess the output of this third, then try it
@14:15
theprimeagen: *concentrating very hard to follow the exact logic behind Javascript's blackmagik type conversion*
chat: uh-huh-huhhuh...he said "bang array"
😂
I love the title change. 😄
The raw string stuff is used when using regex in a language using strings. Everything needs to be backslashed to count in regex, so it need to stay and not "dissapear" as it would in a real string. I did it in python tho so I dont know about javascript, but I assume its the same
HE CHANGED THE TITLE OMG
I got I think 7/10 following along with this video even after studying JS since 1998. The octal one tripped me up because I didn't know offhand how JS would treat the unquoted value 018 given how relatively recent support for octals was finalized (and I don't actively use octals in my own JS anyways). Truthy-falsy ones only trip me up if I don't know which direction JS converts or coerces first when booleans are already involved because I made it a point to drill on that for hours based on this one particular article (from IIRC some Google/Opera dev like Hakon Wium-Lie or maybe jQuery creator John Resig or something) aggregating JS truthiness cases years ago (an article I'm trying to find, with the earliest search results giving me some Stack Overflow answers from 2013 or so instead) and I've literally never intentionally done "bool + bool" in my entire 25+ years of JS anyways.
Finding out about empty array truthiness in this video was genuinely fascinating, BTW.
The best part is JavaScript added “use strict” and none of these are addressed by this flag, you would think that octals would have required the 0o syntax. Maybe they should add a “really use strict” flag!?
"For real this time"
May I introduce you to Perl's pragmas :P
Both 015 and 018 do throw errors in "strict mode" though?
@@fredoverflow You’re right, but how many people use “use strict” because of the limited improvements that come with it? I tried using “use strict” in REPL mode (both console and Node) and that doesn’t work, I should have written it in a file to test.
It should have made coercion apply to only one side of the comparison and only be applied once, arrays should have required to be the same type for all elements, and add boxing of values. With the number of people who create videos like this, it shows that removing these problematic behaviors would lead to less errors for developers.
@@jfftckyou don't need to "use strict" if you use modern JS with modules. If you're still coding in 2015 with Common.js or AMD or something, it's pretty easy to add a build step to add "use strict" to the top of every file.
I am unreasonably perturbed by the fact that `[]` can be coerced into both `true` and `0` depending on the type chosen.
I've used a String constructor inside a Transform stream to tag the strings.
s = new String(s);
s.position = 23;
s.line = 2;
Then I can use that info in error messages generated during parsing. And they all get turned back into literals before returning to the caller.
oh.... that is interesting!
God! This is the best video I watch since the beginning of 2024
Need to update the title as there are two ex-FAANG-ers here now))
Not calling it String.rawdog is a mistake and you can't change my mind.
That raw string thingy would be useful for Latex, I've just done that in py when needing some formulas in graph annotations
You could use the String constructor to convert a value of type `unknown` to a string, because such values do not have the `.toString()` method. Though this is more of TS thing
you'd use the constructor String in a case where you have a defined array of objects holding type/value pairs (i.e. a configuration map) and you want to map over it in your runtime and create the variables.
here's a one liner: `const data=[{t:String,v:'my string'},{t:Number,v:12}];const instances = data.map(({t, v}) => new t(v));`
I did some Performance testing because I have no hobbies, and I was generating giant tables of data with millions of elements. So doing new Array(1000000) reserves the memory cells in your ram to be used for this Array. So you have values that are next to each other. Same when you do some filtering with like while(len){array[len] = --len} it will allocate the values next to each other. If you do an array without a length then push to it, the array can have different adresses so like have gaps in it used by other variables.
I like how Prime says "ha ha, look at chat in disbelief" and continues to be in disbelief for the next question himself 😔
The only reason to use a string constructor is if you've monkeypatched or extended String with additional methods, which you shouldnt do 99% of the time
Edit: ExFAANG Engineer Watches ExFAANG Take JavaScript Quiz
i came here just to comment that, hahahaa
When did he retire?
@@QTA-20 he didnt retire he left netflix last week and gone full time content creator hence the ExFAANG
@@arafays That's really cool. Thanks
3:10 the exact same question was in my midterm a couple of days ago and my smartass for some reason thought that typeof would return a sort of Wrapper class so like actually Number not a string (Java reference)...but that turned out incorrect obviously...
that raw could be used on a template stuff I guess... to avoid extra processing on manipulation, but don't know if it makes sense at all...
Hi!
How called this cmd extension with immediately output?
now it will have to be an ExFAANG
raw strings are great for path names on windows cause of the backslash in the directory tree instead of a forward slash
Principle of most surprise lmao. Actually insane that js became so dominant.
8:42 It would've been fun if the question was baity and said. 0.2+0.3==0.5. _Although_ floating point can have inaccuracies, that's an example that works out.
Apropos \f (also known as ^L or "form feed"): fun fact, GNU source code is partitioned with form feeds. I haven't see anyone else do that, but it's extremely common in GNU projects.
so the only time I've used a raw string was to identify different dating formats or directories with regex. but that was in python, idk if it would have the same application in JS
26:25 BTW, JAVA handles strings with a stringPool. Each unique string has one reference in memory, so comparing the reference or the actual value is the same. Unless you compare “a” == new String(“a”), then the reference is different.
But “a” == “a” is true
Updated title: “ExFAANG Engineer Watches ExFAANG Take JavaScript Quiz”
I suppose that JS victims may use raw strings to genererate dynamic code that includes a call that prints out a new line, for instance.
so much fun
JavaScript and its weird parts remind me of that old show Unsolved Mysteries, the output is a mystery.
9:04 I incorrectly guessed it would be true, just because of the loose equivalence operator instead of a strict one. In my head I figured js would go the extra mile and either round to the same floating point placement or just chop off. But I was wrong lol
So does undefined get converted to a string or number? What about special undefined?
I actually got wrecked by sort implicitly casting to string once. Worst part was that I wasn't actually the one writing the frontend I wrote the backend that consumed the sorted array.
tbf if you expect a sorted array and the client does not send a sorted array, that's an FE issue not a BE issue.
But also there probably shouldn't be the need for a sorted array and the BE should sort the array itself regardless
@@xelspeththis. Everything should be done in the backend except fetch requests, storing cookies/temporary identifier variables, and DOM manip unless you have a specific edge case (such as using WASM or somehow not having a backend for your calculator website). If your company doesn't have control over the full tech stack though, then you're gonna have to contact the frontend devs to redesign your protocols for what data to send over the wire.
lmao, that was a short-lived title.
It's kinda entertaining to see chat slowly become completely hysterical, ngl.
Java will not duplicate strings in the heap when created with double quotes, so "foo" == "foo" will return true even though it is technically comparing references instead of values. You have to explicitly create additional objects with new String() to break the equality.
At 6:50 ish -- As far as I can find, even though it's counter-intuitive, I believe it actually tries to convert the string argument to a number to do the comparison. If you try 5 == '5.00000' it returns true. If it was as simple as the number argument being converted into a string, these would not be loosely equal. Instead '5.00000' becomes 5
*Edit* : Should've watched further, didn't think he'd come back to it. Prime talks about it again around the 9 minute mark
Prime is laughing so hard that he's face is all red
I understood most of these, and I can accept most of the ones I got wrong, but the fact that string literals are not instances of strings despite their prototype being string makes me incredibly angry.
I cannot wait for the Javascript Apocalypse, when Raytheon starts programming nuclear weapons using Node.
Imagine explaining that to your mutant descendants.
String.raw could be used for typing directories ?? Right 🤔
coming back to this after banging my head for a JS Code to work 😂😂
In Python, you use raw strings for RegEx or SQL queries to remove the need to escape everything. So for Python it is as easy as just putting an r in front of the string literal like this r’/t’, but JavaScript has so much more to type that it isn’t reducing the amount you need to type and I would argue that it isn’t making it that much easier to read.
const r = String.raw
I can't see that causing any problems...
There are regex literals for the first case :p But you are right, there actually are custom JS regex implementations as well as sql libraries that use this "tagged string literal" syntax - and the tag used for them is custom and typically shorter (like @shaunpatrick8345 showed, it can be any name in scope). It can be used in any context where you want a custom language string parser or transformer, such as latex, markdown, htmlx, jsx, etc... A tag's implementation has access to and can chose to use both the normal string version as well as the "raw" version in case it doesn't want the backslash escapes to have their regular string meaning. It also has access to interpolated values (parts that are in ${}) so it can escape them as it wants or even bind them as sql statement parameters or use them as jsx attrs or what have you.
String.raw is useful for storing long windows path if you're too lazy to escape the backslashes
You can use "new String" to make strings with the same value which are not equal to each other:
let a = new String("foo")
let b = new String("foo")
a == "foo" // true
a == b // false
Feels like to build css to IE6. Working around all those skill issues...
does anyone have a link to this quiz?
One use case for String constructor is if you want to store other properties against the string (eg isTranslated)
let s = "hello";
s.isTranslated = true
console.log(s, s.isTranslated)
s = new String("hello")
s.isTranslated = true
console.log(s, s.isTranslated)
You could probably use raw strings when sanitizing the user's input.
"I am currently a FAANG developer at this moment"
I'm not sure does that sort hurt more because it is 33 or because I know I would have made the same implementation if I was making it.
In the 2nd one remember 0 is a falsey value. Doesn't matter if it's 0 or '0'.
In the question 4, 0 == '0', '0' is converted to a number.
The specs:
Abstract Equality Comparison (==)
The comparison `x == y,` where x and y are values, produces true or false. Such a comparison is performed as follows:
1. If `Type(x)` is the same as `Type(y)` then
1. 1. Return the result of performing Strict Equality comparison x === y.
2. If x is null and y is undefined, return true.
3. If x is undefined and y is null, return true.
4. If `Type(x)` is Number and `Type(y)` is String, return the result of comparison `x == ToNumber(y)`
5. If `Type(x)` is String and `Type(y)` is Number, return the result of comparison `ToNumber(x) == y`
6. If `Type(x)` is Boolean, return the result of the comparison `ToNumber(x) == y`
7. If `Type(y)` is Boolean, return the result of the comparison `x == ToNumber(y)`
8. If `Type(x)` is either String, Number or Symbol and `Type(y)` is Object, return the result of the comparison `x == ToPrimitive(y)`.
9. If `Type(x)` is Object and `Type(y)` is either String, Number or Symbol, return the result of the comparison `ToPrimitive(x) == y`.
10. Return false.
Valid-ish usecase for String constructor:
stringArray = numberArray.map(String)
to convert an array of numbers to an array of strings representing those numbers, since javascript lacks a method reference operator (Number::toString).
Didn't check for performance, might be better to just x => x + ''
Hot take, everything in this video makes sense. You need to remember that JS was designed for the browser, not the server. This means, its top priority is to handle bugs in a way that does not break up the UI of anything you're interacting with, yes, even at the cost of correctness. You need to have a wider mental model of what its purpose is.
Obviously, if you use it without any restrictions for that initial environmental model, it will be your own fault.
its sudoku time
"new Array" in JS can take a long walk off a short pier
Conner is actually an instructor from AlgoExpert!
For the sorting question, can someone please explain why "const" plays no role in the outcome? In C++ or Rust, I'm pretty sure trying to sort a const vector would be a compile-time error.
const x = []; does not mean x is a constant array; it means x is a constant _reference_ to a mutable array.
This is known as "reference semantics", whereas C++ and Rust default to "value semantics".
now it's an ex-faang developer watches ex-faang developer take javascript quiz
"I am currently a FAANG developer... as of this moment"
Bro was telling us the writing on the wall.
and that my friend, is why i love javascript 😅
every time I hit pause because I thought the in-video pause was on my end, I get back to work.