Just for fun 👉 React vs. jQuery vs. Svelte, same 🐱 app

You know that feeling when you meet an old friend you haven't seen in years? You used to be so close but ...

"Long time huh ..."

"Yeah time flies ... how's the wife?"

"Girlfriend. She's good, just started a new job ..."

"Nice nice ... you still at that startup?"

"Yeah ... it's okay ... you?"

"Nah, new gig last year. Think I told you, dunno"

"Maybe you did, hard to keep track ... liking it?"

A beer or two later and you're back to being best buds. Suddenly it's 1am and a long yawn reminds you that you're not quite so young anymore.

Could it be? Am I really old enough to be gently hungover from two beers with @Smotko?

🤨
— Swizec Teller (@Swizec) May 23, 2019

That's what messing around with jQuery felt like after all these years.

I was bored Monday night and decided to see if I still know how to build with jQuery. Nothing better to do, no pressing ideas, a bit of fun.

Also a favor for a friend who's preparing to talk about React to a bunch of people who've never seen it before 😛

It's funny, jQuery is so old now (2 years since new versions stopped coming) I feel like I almost have to introduce the darn thing. Used to be the backbone of the web, now it's in the dustbin of history.

Pushed web development forward for its entire 10 year run. Oh the memories ...

memory_lane giphy

So, how does jQuery stack up to React and how does React stack up to Svelte? Let's see 👇

React app

Started with a React app. It's what I'm most familiar with right now.

We built a cat app. Fetches 5 cats from thecatapi, shows first cat. Click a button, get more cats.

When app runs out of cats, it fetches more.

function fetchCats(currentCount) {
  const page = Math.ceil(currentCount / 5);
  return fetch(
    `https://api.thecatapi.com/v1/images/search?limit=5&page=${page}&order=Desc`
  ).then(response => response.json());
}

fetchCats returns a promise with a bunch of cats. Pagination works based on current count of cats we've got.

Rendering a list of cats happens in a <Kitties /> component. 'tis but a loop

function Kitties({ cats, count }) {
  return (
    <>
      {cats.slice(0, count).map(cat => (
        <div key={cat.id}>
          <img src={cat.url} alt="Cat image" />
        </div>
      ))}
    </>
  );
}

Take list of cats, count how many the user wants to see, slice the array, render each cat as an image. 👌

Driving this logic with React Hooks isn't bad. React's ergonomics are getting real good.

function App() {
  const [showCount, setShowCount] = useState(1);
  const [cats, setCats] = useState([]);

  useEffect(() => {
    if (cats.length < showCount) {
      fetchCats(showCount).then(newCats => setCats([...cats, ...newCats]));
    }
  }, [cats, showCount]);

  const moreCats = () = > {
    setShowCount(showCount + 1);
  };

  return (
    <div className="App">
      <h1 >These are cats.</h1 >
      <h2 >Cats are cool </h2>
      <Kitties cats={cats} count={showCount} />
      <button onClick={moreCats} >More cats! </button >
    </div >
  );
}

We got useState for the count of cats, and a useEffect to deal with fetching. Fetches on first load and makes sure to fetch more when showCount is bigger than the current amount of cats.

React handles the rest.

magic giphy

jQuery app

The hardest part of building the jQuery version was figuring out how to import jQuery in a modern compiled-JavaScript app. 😂

No seriously, I struggled, tried a bunch of things, and ended up with a good old script tag and a public CDN.

<script src="https://code.jquery.com/jquery-3.4.1.slim.min.js" integrity="sha256-pasqAKBDmFT4eHoN2ndd6lN370kFiGUFyTiUHWhU7k8="
	 crossorigin="anonymous"></script>

People don't do that in real life anymore. It's all import this import that.

For the app itself we used a naive unoptimized approach much like many jQuery apps of old 👉 find div, empty div, render everything from scratch every time.

function renderCats(cats, count) {
  $("#kitties").html("");

  cats.slice(0, count).forEach(cat => {
    $("#kitties").append($("<div >").append($("<img>").attr("src", cat.url)));
  });
}

Notice the mess with creating a small component tree of <div><img></div>? Painful. JSX improved this a lot. Almost can't believe we used to build complex apps like this.

You can see it's slow too.

Open the CodeSandbox, add a couple cats. You'll see the more cats there are the slower the app gets.

Not so with React because React avoids re-rendering components that don't change.

PS: check out this mess of attaching a button click handler and driving the cat fetching logic.

$("button").on("click", () => {
  CatCount += 1;
  
  if (CatCount > Cats.length) {
    // Fetch more cats when we run out
    fetchCats(CatCount).then(newCats => {
      Cats = [...Cats, ...newCats];
      renderCats(Cats, CatCount);
    });
  } else {
    renderCats(Cats, CatCount);
  }
});

🤮

I like hooks.

Svelte app

The Svelte version wins in the immense straightforward simplicity of it all. I'm pretty blown away.

Check out the <Kitty /> component

<script>
    export let id;
    export let url;
</script>

<style >
    img {
      width: 300px;
    }
</style>

<div>
    <img src={url} alt="Kitty pic" />
</div>

Gets an id and a url, has some style, and renders a div with an image. Pretty slick, looks almost like pure HTML.

Then you got the component that drives state and renders a bunch of kitties with a button.

<script>
  import Kitty from "./Kitty.svelte";
  let showCount = 1;
  let cats = [];

  function fetchCats(currentCount) {
    const page = Math.ceil(currentCount / 5);
    return fetch(
      `https://api.thecatapi.com/v1/images/search?limit=5&page=${page}&order=Desc`
    ).then(response => response.json());
  }

  fetchCats(showCount).then(newCats => {
    cats = [...cats, ...newCats];
  });

  function moreCats() {
    showCount += 1;

    if (showCount>  cats.length) {
      fetchCats(showCount).then(newCats => {
        cats = [...cats, ...newCats];
      });
    }
  }
</script>

The script looks similar to React Hooks. You got some variables with state and you got a moreCats method that drives it.

Repeating that array merging logic twice is a little less elegant than the useEffect hook, but probably easier to understand how it works 🤔

Rendering is neat too

<main>
	<h1 >These are cats.</h1 >
  <h2>Cats are cool 😸</h2>
	{#each cats.slice(0, showCount) as {id, url}}
    <Kitty id={id} url={url} />
  {/each}
  <button on:click={moreCats}>More cats! </button >
</main>

Similar to React, but we used {#each} instead of JavaScript's .map. Still not sure how I feel about that but it's pretty readable you gotta admit.

🤔

Between you and me I think React wins this one. Maybe it's because I'm used to it.

But Svelte does look like it might be quicker to grasp for someone who's new to modern JavaScript.

What do you think?

Happy Friday,
~Swizec