Speaker 1: All right, let's kick things off today. We're going deep
Speaker 1: on ACYNK JavaScript and how to write code that's not
Speaker 1: just functional but really sings performance wise.
Speaker 2: Yeah, we're talking speed exactly.
Speaker 1: And to guide us on this journey, we have Kyle
Speaker 1: Simpson's book You Don't Know JS, A sink and Performance.
Speaker 2: It's a fantastic resource, really digs deep.
Speaker 1: I've got to say this book was a game changer
Speaker 1: for me.
Speaker 2: Absolutely.
Speaker 1: When I first started with ACYNK JavaScript, it felt like
Speaker 1: I don't know, my brain was doing backflips.
Speaker 2: It's definitely a mind bender, especially that.
Speaker 1: Whole concept of later. You know how JavaScript handles things
Speaker 1: that can't happen right away right right. It's not exactly intuitive.
Speaker 2: It's like we assume later means well right.
Speaker 1: After now, Yeah, like step one, step two.
Speaker 2: But in javascripts later it's a whole different beast.
Speaker 1: So let's say you're making an ajax call to grab
Speaker 1: some data from a server. Okay, you write the code,
Speaker 1: you make the call, and then you try to log
Speaker 1: the data. You know, right after it seems logical, yeah,
Speaker 1: but then nothing.
Speaker 2: It's like where the data go proof vanish. The trick
Speaker 2: is we're thinking in a straight line but when you're
Speaker 2: dealing with things like timers, clicks, those AgeX responses, we're
Speaker 2: in the land of a synchronicity.
Speaker 1: Okay, so things are getting shuffled around exactly.
Speaker 2: Things don't always happen in a predictable order.
Speaker 1: So how does JavaScript decide what happens now versus what
Speaker 1: gets pushed to this mysterious later.
Speaker 2: It all comes down to this thing called the event loop.
Speaker 1: Okay, the event loop.
Speaker 2: Think of it like a queue, a never ending queue of.
Speaker 1: Tasks, all right. So each task gets.
Speaker 2: Its turn exactly, Each task gets its moment to run,
Speaker 2: and then boom, event loop moves on to the next one.
Speaker 1: It's like a very organized but super fast game of
Speaker 1: musical chairs.
Speaker 2: You got it.
Speaker 1: But what about set time out?
Speaker 2: Ah?
Speaker 1: Set time out is just like chuck the function into
Speaker 1: queue immediately.
Speaker 2: Not quite. It's more like it sets a timer okay,
Speaker 2: and when the timer goes off, it's like the function
Speaker 2: taps the event loop on the shoulder and says, hey,
Speaker 2: I'm ready now.
Speaker 1: Ah. It's like a reservation system for our code.
Speaker 2: I like that, a reservation system.
Speaker 1: But this brings up something that's always tripped me up.
Speaker 1: What's concurrency? Ah? Concurrency what happens when multiple things are
Speaker 1: trying to happen at the same time.
Speaker 2: It's a great question and important to remember. Even though
Speaker 2: JavaScript doesn't have traditional threads, we still have to deal
Speaker 2: with concurrency because at its heart it's single threaded.
Speaker 1: So it's like having one chef trying to cook multiple
Speaker 1: dishes at once.
Speaker 2: Exactly. They can only work on one thing at a time,
Speaker 2: but they've got to keep switching back and forth.
Speaker 1: So how do we make sure we're not creating kitchen
Speaker 1: chaos in our code? Right?
Speaker 2: We don't want everything burning?
Speaker 1: What happens when multiple functions try to access and you know,
Speaker 1: change the same data at the same time.
Speaker 2: It can get messy. But one way to manage this
Speaker 2: is using something called mutual exclusion.
Speaker 1: Mutual exclusion okay, like.
Speaker 2: Putting a lock on a shared resource.
Speaker 1: So only one function can access it at a time.
Speaker 2: You got it. You can think of it like a
Speaker 2: simple if statement that checks if a variable is being used.
Speaker 1: So it's like those occupied signs on a restroom stall.
Speaker 2: Perfect analogy.
Speaker 1: It's got a wait, it's turned exactly now, what about
Speaker 1: breaking down those tasks into smaller chunks?
Speaker 2: Ah, you're talking about cooperative concurrency.
Speaker 1: That's it.
Speaker 2: It's all about sharing the stage.
Speaker 1: So instead of one function hogging the event loop for ages,
Speaker 1: we break.
Speaker 2: It down right into smaller steps, give other functions a
Speaker 2: chance to run, so.
Speaker 1: We avoid that event loop traffic jam exactly. Okay. I
Speaker 1: gotta be honest, though, the fact that JavaScript can actually
Speaker 1: re order statements in my code, that kind of freaks
Speaker 1: me out.
Speaker 2: I get it. It feels like our code is being
Speaker 2: rearranged behind our backs, right, But remember the JavaScript engine,
Speaker 2: it's smart, okay. It's always looking for ways to optimize
Speaker 2: our code, and sometimes that means rearranging things as long
Speaker 2: as the final result is the same.
Speaker 1: So it's like having a super efficient editor.
Speaker 2: Exactly.
Speaker 1: They clean up our writing, but the meaning stays the
Speaker 1: same precisely. That makes me feel a bit better.
Speaker 2: Good, good, But it still.
Speaker 1: Makes it hard to picture, you know, what happens when,
Speaker 1: especially with all these asynchronous events flying around.
Speaker 2: It's true we're wired for linear thinking, but asynchronous code
Speaker 2: it's much more fluid. Ye think about trying to run
Speaker 2: errands and take phone calls at the same time. Oh yeah,
Speaker 2: You start one task, get interrupted by a call, go
Speaker 2: back to the task, interrupted again.
Speaker 1: It's impossible to plan everything perfectly in a straight line, exactly.
Speaker 2: You can't predict when those calls are going to come in.
Speaker 1: And I feel like that chaotic feeling gets amplified when
Speaker 1: we start using nested callbacks.
Speaker 2: Oh, nested callbacks they can get out of hand.
Speaker 1: It's like following a recipe where every step sends you
Speaker 1: on a wild goose chase for another ingredient.
Speaker 2: Right, You're jumping all over the place.
Speaker 1: And then you end up with a kitchen that looks
Speaker 1: like a tornado hit.
Speaker 2: It, exactly. And nested callbacks they can turn into a
Speaker 2: tangled mess.
Speaker 1: They make our code harder to understand, harder to debug,
Speaker 1: harder to maintain. Absolutely, which brings us to the well,
Speaker 1: the darker side of callbacks. Ooh, what's that the trust issues?
Speaker 2: Trust issues with a our own code.
Speaker 1: Yeah, shouldn't we be able to trust ourselves ideally?
Speaker 2: Yes, but remember in this acinc world, things get unpredictable.
Speaker 2: Even our own code can behave in ways we don't expect,
Speaker 2: especially when we're dealing with external libraries.
Speaker 1: Okay, you're losing me a little.
Speaker 2: Okay, imagine this. Yeah, you're adding a third party analytics
Speaker 2: tool to your website. You know, for tracking purchases. Okay, yeah,
Speaker 2: you hand over your purchase data to their library. Everything
Speaker 2: seems to be working fine. You pat yourself on the back. Job,
Speaker 2: well done, right, good job. Months later, your boss calls panicked.
Speaker 2: Oh no, a customer was charged five times for the
Speaker 2: same item.
Speaker 1: Oh that's a nightmare.
Speaker 2: It is. And after some frantic debugging, you find out
Speaker 2: that the analytics library was silently retrying the purchase callback
Speaker 2: multiple times, leading to those duplicate charges.
Speaker 1: It's like handing over the keys to your car and
Speaker 1: hoping they won't go on a joy ride.
Speaker 2: That's exactly the problem with callbacks, this inversion of control.
Speaker 1: We're handing over control and just hoping for the best.
Speaker 2: Right, But there's a better way.
Speaker 1: Tell me, there's a better way. Promises promises, those sound promising,
Speaker 1: They tell me more.
Speaker 2: A promise is essentially a contract for a future.
Speaker 1: Value, so like a guarantee in a way.
Speaker 2: Yeah, it's like saying, I promise to get back to
Speaker 2: you with the result of this operation.
Speaker 1: Whether it's a success or a failure.
Speaker 2: Exactly.
Speaker 1: So, instead of relying on this potentially flaky callback, we
Speaker 1: have a more structured approach.
Speaker 2: It's more reliable. I like it, and with promises, we
Speaker 2: keep control over the flow of execution.
Speaker 1: Okay, so we get to decide what happens next exactly.
Speaker 2: We define what should happen when the promise is fulfilled
Speaker 2: meaning the operation was successful, or rejected meaning there was
Speaker 2: an error.
Speaker 1: Okay, promises sound like a much safer bet they are.
Speaker 1: Could you walk me through an example. Maybe you know
Speaker 1: with our trustee ajax call.
Speaker 2: Absolutely, So instead of passing a callback function to that
Speaker 2: ajax call, we create a promise that represents the result
Speaker 2: of the request Okay, and then, using the then method,
Speaker 2: we specify what should happen when the promise resolves successfully.
Speaker 1: So it's like, if this happens, then do this you
Speaker 1: got it?
Speaker 2: And if something goes wrong, we can use the catch
Speaker 2: method to handle the error gracefully prevents our app from crashing.
Speaker 1: Okay. So promises make our asynchronous code more robust and
Speaker 1: predictable exactly. But what about when we have multiple asynchronous
Speaker 1: operations we need to do in sequence.
Speaker 2: Ah, That's where the magic of promise chaining comes in.
Speaker 1: Okay, promise chaining, you can use the.
Speaker 2: Then method to chain together a series of asynchronous steps.
Speaker 1: Each one depending on the one before it exactly.
Speaker 2: It's like a domino effect. Each step triggers the next.
Speaker 1: Okay, so instead of juggling all these promises at once,
Speaker 1: we create this smooth, organized flow precisely.
Speaker 2: It's all about creating a clear sequence of events.
Speaker 1: I love it. But what about situations where we have
Speaker 1: multiple promises happening concurrently, Like let's say we need to
Speaker 1: fetch data from multiple URLs at the same time.
Speaker 2: Ah, for that, we have promise at all at all.
Speaker 2: It's like waiting for all your friends to get ready
Speaker 2: before you head out for the night.
Speaker 1: You pass it in an array of promises.
Speaker 2: Yep, and it gives you back a new promise that
Speaker 2: resolves when all of those promises have resolved.
Speaker 1: So it's like okay, everyone's here, let's go exactly.
Speaker 2: And the best part is Promise all gathers all the
Speaker 2: results from those promises into a nice array, so you
Speaker 2: can work with the combined data easily.
Speaker 1: Okay, So promises can handle these complex scenarios, both sequential
Speaker 1: and concurrent.
Speaker 2: They're very versatile.
Speaker 1: I'm impressed I did. But earlier we were talking about
Speaker 1: you know, those nested callback nightmares with event handlers. Oh yeah,
Speaker 1: can promises help us out there too.
Speaker 2: They can, but we got to be careful. Okay, if
Speaker 2: we're not careful, we might just be trading one type
Speaker 2: of complexity for another.
Speaker 1: Okay.
Speaker 2: Creating a new promise chain inside each event handler can get.
Speaker 1: Messy, right, redundant code.
Speaker 2: It makes things hard to manage.
Speaker 1: So what's the secret to using promises effectively with event handlers.
Speaker 2: It's about shifting our perspective. Instead of creating a promise
Speaker 2: chain within the event handler, we can use observables.
Speaker 1: Observables. You mentioned those earlier. They sound pretty advanced.
Speaker 2: They're powerful, but the core concept is actually quite simple. Okay,
Speaker 2: think of an observable like a stream of events, right,
Speaker 2: like a flow of data exactly. You can subscribe to
Speaker 2: an observable and react to each event that comes through
Speaker 2: that stream using you guessed it promises.
Speaker 1: So it's like setting up a sensor. When it detects
Speaker 1: a change, it triggers a specific action.
Speaker 2: Perfect analogy.
Speaker 1: Okay, So observables sound like a whole other deep dive.
Speaker 2: We could definitely spend a whole episode on those, but.
Speaker 1: For now, let's move on to generators.
Speaker 2: Generators another powerful tool in our acinc toolkit.
Speaker 1: I gott admit I haven't quite wrapped my head around
Speaker 1: them yet.
Speaker 2: They're a really cool way to write asynchronous code that
Speaker 2: looks and feels synchronous.
Speaker 1: Wait, so you can write ACYNC code that looks like
Speaker 1: it's running in a stray line.
Speaker 2: You got it. Generators let you pause and resume execution
Speaker 2: using the yield keyword, like.
Speaker 1: Having a pause button for our code.
Speaker 2: Exactly. You can pause the execution, wait for an asynchronous
Speaker 2: operation to complete, and then resume right where you left off.
Speaker 1: Okay, my mind is blown. How does that even work?
Speaker 2: Imagine you have a function that needs to fetch data
Speaker 2: from a server. With a generator, you can yield control
Speaker 2: at the point where the request is made.
Speaker 1: Okay, Then when the data is available, you can resume
Speaker 1: the function right where you left off.
Speaker 2: So it's like breaking down a long task into smaller,
Speaker 2: more manageable chunks exactly.
Speaker 1: And the best part is the code inside the generator
Speaker 1: reads like a synchronous story.
Speaker 2: Okay, this is starting to make sense. Good, good, But
Speaker 2: how do we actually use this with real world asynchronous operations.
Speaker 1: That's where promises come back into play. Okay, we can
Speaker 1: create a promise that wraps the execution of the generator
Speaker 1: using yield to delegate to promises for asynchronous tasks.
Speaker 2: So we get the best of both worlds exactly.
Speaker 1: The synchronous looking code of generators combined with the trust
Speaker 1: and composability of promises.
Speaker 2: Wow, that's powerful.
Speaker 1: It is.
Speaker 2: But what about those of us who are still supporting
Speaker 2: older browsers, you know, the ones that haven't quit caught
Speaker 2: up to the whole generator scene.
Speaker 1: Don't worry, we got you covered.
Speaker 2: Okay.
Speaker 1: We can use a technique called transpiling, which basically translates
Speaker 1: our fancy ES six code, including generators, into code that
Speaker 1: older browsers can understand.
Speaker 2: So it's like a universal translator for JavaScript exactly.
Speaker 1: Okay, so we have options even when we're dealing with
Speaker 1: those legacy browsers.
Speaker 2: Always good to have options.
Speaker 1: I feel like we've covered so much ground already.
Speaker 2: We have, but we're just getting started.
Speaker 1: Oh man, my brain is already full.
Speaker 2: It's a lot to take in. But it's exciting stuff.
Speaker 1: It is exciting, and you know what, I'm ready to
Speaker 1: dive even deeper into the world of JavaScript performance.
Speaker 2: Let's do it.
Speaker 1: But first, a quick message from our sponsor, welcome back.
Speaker 1: Before the break, we were getting into generators and promises.
Speaker 1: How they can wrangle that asynchronous JavaScript all its quirks. Yeah, exactly.
Speaker 1: But there's another powerful tool we've got to talk about,
Speaker 1: and it's web workers. Ah.
Speaker 2: Yes, web workers.
Speaker 1: These things bring true parallelism to JavaScript.
Speaker 2: They really do.
Speaker 1: Imagine being able to run multiple pieces of code simultaneously,
Speaker 1: like having a whole team of chefs in the kitchen instead.
Speaker 2: Of just won much more efficient.
Speaker 1: Right, No more bottlenecks at the stove, exactly. But how
Speaker 1: do these webworkers actually work? Do they have their own
Speaker 1: like little JavaScript universe in a way.
Speaker 2: Yeah, Each webworker runs in its own isolated environment, separate
Speaker 2: from the main thread.
Speaker 1: So they're like independent apartments in a building.
Speaker 2: That's a good way to put it.
Speaker 1: They're separate, but can still, you know, communicate exactly.
Speaker 2: They communicate through a system called message passing.
Speaker 1: So it's like sending notes back and forth precisely.
Speaker 2: They can request data, send results, coordinate their actions all
Speaker 2: without stepping on each other's toes.
Speaker 1: Very civilized it is. But what about data structures? Can
Speaker 1: web workers access the same arrays and objects as the
Speaker 1: main thread?
Speaker 2: Not directly, no, okay, But there's this clever mechanism called transferable.
Speaker 1: Objects transferable objects.
Speaker 2: It allows them to efficiently share data instead of copying,
Speaker 2: which can be slow. They transfer ownership, so.
Speaker 1: It's like handing off a baton in a relay race.
Speaker 2: Perfect analogy. Only one runner can hold the baton at
Speaker 2: a time, but they pass it on smoothly.
Speaker 1: And that's way faster than making copies.
Speaker 2: Much faster, especially when you're dealing with large amounts of data.
Speaker 1: Okay, webworkers sound amazing, but are there any limitations?
Speaker 2: Yeah? Well, every superhero has their kryptonite, right. Webworkers don't
Speaker 2: have direct access to the dom.
Speaker 1: The dom, so they can't manipulate the user interface.
Speaker 2: They're more like behind the scenes heroes, crunching numbers, processing data,
Speaker 2: but not messing with the visual stuff.
Speaker 1: Got it. They're like the engine under the hood, not
Speaker 1: the flashy pain job exactly. But what about libraries in
Speaker 1: external code? Can they use those?
Speaker 2: Absolutely? Webworkers can use a function called import scripts to
Speaker 2: load external JavaScript files. It's like giving them a whole toolbox.
Speaker 1: So we could equip them for any task you got it.
Speaker 1: But what about older browsers, you know, the ones that
Speaker 1: haven't gotten the memo about web workers.
Speaker 2: For those cases, we have polyphills polyphills. They can emulate
Speaker 2: the behavior of webworkers even in those older browsers.
Speaker 1: It's like finding a vintage record player that can play
Speaker 1: modern digital music exactly.
Speaker 2: You get the functionality, even if the browser doesn't natively
Speaker 2: support it.
Speaker 1: That's awesome, it is. Okay, before we move on, I've
Speaker 1: heard this term thrown around SIMD. What is that all about?
Speaker 2: SIMD stands for single instruction multiple data.
Speaker 1: Okay, that sounds intense.
Speaker 2: It's a way to perform the same operation on multiple
Speaker 2: pieces of data at the same time.
Speaker 1: So it's like having an assembly line of robots, each
Speaker 1: one doing the same task but on a different item.
Speaker 2: Perfect analogy. It's mass production for data processing, very efficient,
Speaker 2: incredibly efficient, especially for computations involving large data sets.
Speaker 1: Okay, so we've got web workers for task parallelism, multiple
Speaker 1: workers tackling different tasks, right, and then sim and D
Speaker 1: for data parallel processing multiple pieces of data at once.
Speaker 2: You got it. It's all about finding the right tool
Speaker 2: for the job, leveraging parallelism to boost performance.
Speaker 1: This is blowing my mind. JavaScript can do so much
Speaker 1: these days.
Speaker 2: It really can, and it's only getting more powerful.
Speaker 1: So what's next on the horizon? For JavaScript performance.
Speaker 2: Well, there are some exciting proposals for new features that
Speaker 2: could bring even more parallelism to JavaScript, potentially allowing for
Speaker 2: direct threaded functionality.
Speaker 1: Wait direct threads in JavaScript.
Speaker 2: That's the idea. It's still early days, but the possibilities
Speaker 2: are huge.
Speaker 1: So we might be able to write truly parallel code
Speaker 1: without relying on web workers or SIMD.
Speaker 2: That's the goal.
Speaker 1: That would be a game changer.
Speaker 2: It would revolutionize how we approach JavaScript performance.
Speaker 1: This deep dive has been like a crash course in
Speaker 1: JavaScript optimization.
Speaker 2: We've covered a lot of ground.
Speaker 1: From the event loop, to concurrency, to web workers to SIMD.
Speaker 1: I feel like a JavaScript performance in ninja.
Speaker 2: You're well on your way, But how do.
Speaker 1: We actually know if our code is performing? Well? We
Speaker 1: can write all this async code, but how do we
Speaker 1: measure its efficiency?
Speaker 2: That's where benchmarking comes in.
Speaker 1: Benchmarking okay, it's the.
Speaker 2: Process of systematically measuring the performance of your code, seeing
Speaker 2: how long it takes to execute certain operations. It's like
Speaker 2: taking your code for a test drive on a racetrack.
Speaker 1: I love that analogy.
Speaker 2: You see how fast it can go.
Speaker 1: So how do we actually benchmark our JavaScript code? Do
Speaker 1: we need special equipment.
Speaker 2: Not necessarily. For simple tests, you can use the built
Speaker 2: inconsole dot time and console dot time end methods.
Speaker 1: Okay, so we can get a quick snapshot using the
Speaker 1: console exactly.
Speaker 2: It's like using a stopwatch to time your code.
Speaker 1: But I'm guessing there are more sophisticated tools out there
Speaker 1: for serious benchmarking.
Speaker 2: Absolutely. If you need more detailed measurements, you can use
Speaker 2: libraries like benchmark dot js.
Speaker 1: Benchmark dot js okay.
Speaker 2: It allows you to run multiple tests, collect data, even
Speaker 2: calculate the margin of error.
Speaker 1: Wow, margin of error. We're getting serious now.
Speaker 2: It's all about getting and reliable data so you can
Speaker 2: make informed decisions.
Speaker 1: So let's say we've run our benchmarks, we have some data.
Speaker 1: Now comes the fun part tuning. Where do we even begin.
Speaker 2: The first step is to identify the bottlenecks, the parts
Speaker 2: of your code that are slowing things down.
Speaker 1: So it's like finding the weak link in a chain.
Speaker 2: Precisely. Once you've found the bottlenecks, you can start exploring
Speaker 2: different optimization strategies.
Speaker 1: It's like being a code detective searching for clues to
Speaker 1: improve performance.
Speaker 2: Exactly, And just like a good detective, you need the
Speaker 2: right tools and techniques.
Speaker 1: So what are some common strategies for optimizing JavaScript code.
Speaker 2: One common approach is to reduce the number of function calls.
Speaker 1: Okay. Function calls can.
Speaker 2: Be expensive, they can be, so minimizing their use can
Speaker 2: often lead to performance gains.
Speaker 1: So it's all about streamlining the flow of execution.
Speaker 2: Exactly, make it as smooth as possible.
Speaker 1: What about object creation? I've heard that creating lots of
Speaker 1: objects can slow things down.
Speaker 2: You're right. Object creation, especially for large or complex objects,
Speaker 2: can be a performance hit.
Speaker 1: Okay, So minimize unnecessary object creation.
Speaker 2: That's a good rule of thumb.
Speaker 1: Got it. Reduce objects, streamline functions, check and check. But
Speaker 1: what about arrays? Any tips for optimizing code that works
Speaker 1: with a RaSE?
Speaker 2: Absolutely? For example, when you're looping through an array, it's
Speaker 2: often more efficient to cache the length of the array
Speaker 2: rather than recalculating it on each iteration.
Speaker 1: Ah. So it's like remembering how many ingredients you need
Speaker 1: instead of recounting them every time you add something to
Speaker 1: the bowl.
Speaker 2: Exactly. It's a little shortcut for your code.
Speaker 1: Very clever. I like it. Good, good, Okay. What about
Speaker 1: async specific optimizations? Any things to keep in mind when
Speaker 1: working with promises, generators, web workers definitely.
Speaker 2: When working with promises, it's generally best to resolve or
Speaker 2: reject them as soon as possible. No need to.
Speaker 1: Delay, okay, So keep those promises flowing exactly.
Speaker 2: And with generators, remember that each yield represents a potential
Speaker 2: pause point. Use them strategically, like.
Speaker 1: Hitting the pause button on a movie.
Speaker 2: Right. You don't want to pause every few seconds, got it?
Speaker 1: Use yield strategically and keep those promises moving precisely. But earlier,
Speaker 1: you mentioned that different JavaScript engines might optimize code in
Speaker 1: different ways.
Speaker 2: That's true.
Speaker 1: Does that mean we need to write code that's specifically
Speaker 1: tailored to each engine?
Speaker 2: Ideally we want our code to perform well everywhere, But
Speaker 2: the reality is different engines have their own quirks.
Speaker 1: It's like trying to write a song that sounds good
Speaker 1: on both a grand piano and a ukulele exactly.
Speaker 2: So how do we strike that balance?
Speaker 1: How do we write code that's universally optimized?
Speaker 2: Start with general optimization principles that apply across all engines,
Speaker 2: and then if you have specific bottlenecks, you can use
Speaker 2: feature detection trure detection okay, to identify the current engine
Speaker 2: and apply targeted optimizations, so.
Speaker 1: We're gathering intel on the environment before we deploy our code.
Speaker 2: Exactly. It's all about being adaptable, understanding the nuances of
Speaker 2: different JavaScript environments.
Speaker 1: Okay, that makes senseick, But there's one more optimization concept
Speaker 1: I want to talk about. What's that pail call optimization?
Speaker 2: Ah y, Yes. TCO a powerful technique for improving the
Speaker 2: performance of recursive functions.
Speaker 1: Cursive functions those are the ones that call themselves, right,
Speaker 1: that's right, But I've heard they can be dangerous because
Speaker 1: of stack overflow errors.
Speaker 2: They can be If a recursive function calls itself too
Speaker 2: many times, it can fill up the call stack and
Speaker 2: crash the program. That sounds bad, it can be, But
Speaker 2: TCO prevents this by optimizing how recursive functions are executed.
Speaker 1: So TCO is like a safety net for recursive functions.
Speaker 2: You could say that in a nutshell, when a function
Speaker 2: call is in the tail position, meaning it's the last
Speaker 2: operation performed by the function, the engine can reuse the
Speaker 2: existing stack frame instead of creating a new one.
Speaker 1: So it's like recycling those.
Speaker 2: Stack frames exactly, saves memory and improves performance.
Speaker 1: That's very clever. TCO sounds like a must have for
Speaker 1: any serious recursive function.
Speaker 2: It is, and luckily ES six made TCO a requirement,
Speaker 2: so modern JavaScript engines should all support it.
Speaker 1: That's great. News is okay. We've covered a ton of
Speaker 1: ground here benchmarking, tuning different JavaScript engines TCO. My head
Speaker 1: is spinning.
Speaker 2: That's a lot to take in. But you're doing great.
Speaker 1: I'm starting to feel like I can actually write JavaScript
Speaker 1: code that performs well.
Speaker 2: You're well on your way. Remember, optimizing JavaScript performance is
Speaker 2: an ongoing journey. There's always more to learn and explore.
Speaker 1: It's a marathon, not a sprint exactly. But before we
Speaker 1: get too carried away with all this performance talk, I
Speaker 1: want to shift gears a bit and talk about something
Speaker 1: equally important. Readability.
Speaker 2: Ah. Yes, readability just as important as performance, because what.
Speaker 1: Good is super fast code if no one can understand it?
Speaker 2: Exactly? Writing readable code is crucial for collaboration, maintainability, and
Speaker 2: your own sanity.
Speaker 1: I've definitely encountered some code that felt like deciphering ancient hieroglyphics.
Speaker 2: We have all been there.
Speaker 1: It's like, what was I thinking when I wrote this?
Speaker 2: But writing readable code is not just about avoiding confusion.
Speaker 2: It's about creating code that's enjoyable to work with.
Speaker 1: Okay, making the code a pleasure.
Speaker 2: To read, exactly, code that's clear, concise, and expresses your
Speaker 2: intent in a way that others can easily understand.
Speaker 1: So how do we actually achieve that? How do we
Speaker 1: write code that's both efficient and elegant? And we're back.
Speaker 1: We were just talking about how important it is to
Speaker 1: write readable code, code does not just functional, but actually
Speaker 1: enjoyable to.
Speaker 2: Work with, right, Because we all want our code to
Speaker 2: be elegant, but let's face it, we also want to
Speaker 2: squeeze every ounce of performance out of our JavaScript.
Speaker 1: Absolutely, we're all about speed. But how do we find
Speaker 1: that balance between writing beautiful code and making it lightning fast?
Speaker 2: It's a constant juggling act, and I think sometimes we
Speaker 2: get caught up in what we call micro optimizations. You know,
Speaker 2: those tiny tweaks that promise a performance boost, but do
Speaker 2: they actually make a real difference.
Speaker 1: Oh, I've definitely been down that rabbit hole before, like
Speaker 1: obsessing over whether to use plus plus A or A
Speaker 1: plus plus.
Speaker 2: Yeah, we've all been there.
Speaker 1: Did it really matter in the end?
Speaker 2: Probably not. It's easy to get fixated on those benchmarks
Speaker 2: that focus on isolated operations. But those tiny differences they
Speaker 2: often become insignificant when you look at the whole picture
Speaker 2: of a complex application.
Speaker 1: It's like rearranging the furniture in your house to save
Speaker 1: a few steps. Technically more efficient, but does it really change.
Speaker 2: Your life exactly. Context is key. Optimize for clarity and
Speaker 2: maintainability first. Then if you have performance bottlenecks, you can
Speaker 2: look at those micro optimizations. Right, don't sweat the small
Speaker 2: stuff exactly, focus on the big picture.
Speaker 1: But even when we are focused on those bigger optimizations,
Speaker 1: we have to remember that different JavaScript engines might optimize
Speaker 1: things differently.
Speaker 2: That's true. The javascriptspec gives engines a lot of leeway
Speaker 2: in how they optimize code. It's like having different chefs
Speaker 2: using the same recipe but maybe adding their own personal flare.
Speaker 1: So our code might perform differently depending on the engine
Speaker 1: it's running on, even if we follow the same best practices.
Speaker 2: Yep, exactly. Some times what was considered an optimization, well
Speaker 2: it's not the best approach anymore.
Speaker 1: You mean, like what worked yesterday doesn't necessarily work today.
Speaker 2: Right. For example, years ago, using a ray dot joined
Speaker 2: to put strings together was generally faster than using the
Speaker 2: plus operator. Interesting, But then JavaScript engines evolved got smarter.
Speaker 2: They did, and they introduced optimizations for the plus operator,
Speaker 2: and it became more efficient. So the landscape shifted.
Speaker 1: So what's the takeaway here?
Speaker 2: Be adaptable, stay informed about what's going on with JavaScript engines.
Speaker 2: What's best practiced today might not be tomorrow.
Speaker 1: Got to stay ahead of the curve exactly.
Speaker 2: But there's another interesting thing about these engines.
Speaker 1: Oh, what's that.
Speaker 2: They don't always execute code in the exact order it's written.
Speaker 1: Wait, hold on, they could just rearrange my code.
Speaker 2: Well, not rearrange randomly, but optimize. Okay, the engine can
Speaker 2: analyze your code figure out if reordering some statements would
Speaker 2: improve performance without changing the outcome, like a super efficient editor.
Speaker 1: So they're making my code better without messing with the
Speaker 1: meaning exactly. Okay, I can live with that. Good. So
Speaker 1: we need to like trust the engine, but also be
Speaker 1: aware of this reordering thing exactly.
Speaker 2: Now, speaking of optimization, there's one more concept I want
Speaker 2: to bring up, tail call optimization.
Speaker 1: Tail call optimization or TCO as.
Speaker 2: The cool kids call it, right, it can dramatically improve
Speaker 2: the performance of recursive functions.
Speaker 1: Okay, remind me recursive functions those are the ones that
Speaker 1: call themselves.
Speaker 2: That's right, but they can be tricky because of those
Speaker 2: pesky stack overflow errors.
Speaker 1: Yeah, those can be a real headache. So TCO helps
Speaker 1: prevent those exactly.
Speaker 2: With TCO, when a function call is in the tail position,
Speaker 2: meaning it's the very last thing the function does, the
Speaker 2: engine can optimize how it runs.
Speaker 1: So instead of creating a brand new stack frame every
Speaker 1: time the function calls itself, it reuses the existing.
Speaker 2: One precisely like recycling.
Speaker 1: Very efficient, very clever. So TCO definitely something to keep
Speaker 1: in mind when working with recursive functions.
Speaker 2: It is, and luckily modern jobscript engines all support it.
Speaker 1: Well, that's a relief, it is. It feels like we've
Speaker 1: covered a whole universe of JavaScript performance in this deep dive.
Speaker 1: From the event loop and concurrency to promises and generators,
Speaker 1: web workers, benchmarking, tuning, and now TCO.
Speaker 2: We've been on quite a journey.
Speaker 1: My brain is overflowing, but in a good way.
Speaker 2: It's a lot to absorb, but the key is to
Speaker 2: remember that this is just the beginning, right.
Speaker 1: There's always more to learn and explore in the world's
Speaker 1: of javascripts.
Speaker 2: Exactly, keep experimenting, keep pushing those boundaries and most importantly,
Speaker 2: have fun with it.
Speaker 1: Couldn't have set it better myself, so to our listeners,
Speaker 1: thanks for joining us on this deep dive. Keep learning,
Speaker 1: keep coding, and keep that JavaScript running smooth and fast.