PyScript vs. JavaScript: A Battle of Web Titans

We’re delving into frontend web development today, and you might be thinking: what does this have to do with Data Science? Why is Towards Data Science publishing a post related to web dev?

Well, because data science isn’t only about building powerful models, engaging in advanced analytics, or cleaning and transforming data—presenting the results is also a key part of our job. And there are several ways to do it: PowerPoint presentations, interactive dashboards (like Tableau), or, as you’ve guessed, through a website.

Speaking from personal experience, I work daily on developing the website we use to present our data-driven results. Using a website instead of PowerPoints or Tableau has many advantages, with freedom and customization being the biggest ones.

Even though I’ve come to (kind of) enjoy JavaScript, it will never match the fun of coding in Python. Luckily, at FOSDEM, I learned about PyScript, and to my surprise, it’s not as alpha as I initially thought.

But is that enough to call it a potential JavaScript replacement? That’s exactly what we’re going to explore today.

JavaScript has been the king of web development for decades. It’s everywhere: from simple button clicks to complex web apps like Gmail and Netflix. But now, there’s a challenger stepping into the ring—PyScript—a framework that lets you run Python in the browser without needing a backend.Sounds like a dream, right? Let’s break it down in an entertaining head-to-head battle between these two web technologies to see if PyScript is a true competitor!

Round 1: What Are They?

This is like the Jake Paul vs Mike Tyson battle: the new challenger (PyScript) vs the veteran champion (JS). Don’t worry, I’m not saying today’s battle will be a disappointment as well.

Let’s start with the veteran: JavaScript.

Created in 1995, JavaScript is the backbone of web development.

Runs natively in browsers, controlling everything from user interactions to animations.

Supported by React, Vue, Angular, and a massive ecosystem of frameworks.

Can directly manipulate the DOM, making web pages dynamic.

Now onto the novice: PyScript.

Built on Pyodide (a Python-to-WebAssembly project), PyScript lets you write Python inside an HTML file.

No need for backend servers—your Python code runs directly in the browser.

Can import Python libraries like NumPy, Pandas, and Matplotlib.

But… it’s still evolving and has limitations.

This last but is a big one, so JavaScript wins the first round!

Round 2: Performance Battle

When it comes to speed, JavaScript is like Usain Bolt—optimized and blazing fast. It runs natively in the browser and is fine-tuned for performance. On the other hand, PyScript runs Python via WebAssembly, which means extra overhead.

Let’s use a real mini-project: a simple counter app. We’ll build it using both alternatives and see which one performs better.

JavaScript

<button onclick=”increment()”>Click Me</button>
<p id=”count”>0</p>
<script>
let count = 0;
function increment() {
count++;
document.getElementById(“count”).innerText = count;
}
</script>

PyScript

<py-script>
from pyscript import display
count = 0

def increment():
global count
count += 1
display(count, target=”count”)
</py-script>
<button py-click=”increment()”>Click Me</button>
<p id=”count”>0</p>

Putting them to the test:

JavaScript runs instantly.

PyScript has a noticeable delay.

End of round: JS increases its advantage making it 2-0!

Round 3: Ease of Use & Readability

Neither of both languages is perfect (for example, neither includes static typing), but their syntax is very different. JavaScript can be quite messy:

const numbers = [1, 2, 3];
const doubled = numbers.map(num => num * 2);

While Python is far easier to understand:

numbers = [1, 2, 3]
doubled = [num * 2 for num in numbers]

The fact that PyScript lets us use the Python syntax makes it the round winner without a doubt. Even though I’m clearly biased towards Python, the fact that it’s beginner-friendly and usually more concise and simple than JS makes it better in terms of usability.

The problem for PyScript is that JavaScript is already deeply integrated into browsers, making it more practical. Despite this, PyScript wins the round making it 2-1.

One more round to go…

Round 4: Ecosystem & Libraries

JavaScript has countless frameworks like React, Vue, and Angular, making it a powerhouse for building dynamic web applications. Its libraries are specifically optimized for the web, providing tools for everything from UI components to complex animations.

On the other hand, PyScript benefits from Python’s vast ecosystem of scientific computing and data science libraries, such as NumPy, Pandas, and Matplotlib. While these tools are excellent for Data Visualization and analysis, they aren’t optimized for frontend web development. Additionally, PyScript requires workarounds to interact with the DOM, which JavaScript handles natively and efficiently.

While PyScript is an exciting tool for embedding Python into web applications, it’s still in its early stages. JavaScript remains the more practical choice for general web development, whereas PyScript shines in scenarios where Python’s computational power is needed within the browser.

Here’s a table summarizing some of the key components 

FeatureJavaScriptPyScriptDOM ControlDirect & instantRequires JavaScript workaroundsPerformanceOptimized for browsersWebAssembly overheadEcosystemHuge (React, Vue, Angular)Limited, still growingLibrariesWeb-focused (Lodash, D3.js)Python-focused (NumPy, Pandas)Use CasesFull web appsData-heavy apps, interactive widgets

Round’s verdict: JavaScript dominates in general web dev, but Pyscript shines for Python-centric projects.

Final Verdict

This was a quick fight! We still don’t know who won though…

Time to reveal it:

If you’re building a full web app,  JavaScript is the clear winner.

If you’re adding Python-powered interactivity (e.g., data visualization), PyScript could be useful.

With that said, it’s fair to say that JavaScript (and its derivatives) still remains the web’s frontend best option. However, the future of PyScript is one to watch: If performance improves and it gets better browser integration, PyScript could become a strong hybrid tool for Python developers willing to incorporate more data-related tasks on the frontend.

Winner: JavaScript.

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