Python vs. JavaScript - key differences

Sunscrapers Team

24 October 2022, 8 min read

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What's inside

  1. Intro to Python and JavaScript
  2. Python vs. JavaScript
  3. When to choose Python and when to use JavaScript
  4. Summary

Intro to Python and JavaScript

Before we start digging into the differences between Python and JavaScript, let’s go through a few basic facts about both languages:

Python is a high-level, general-purpose programming language, which means it can be used to solve any problem that can be written in code.

It is widely used in scientific and specialized applications like data science, artificial intelligence, machine learning, computer science education, computer vision and image processing, medicine, biology, and even astronomy.

Thanks to web development frameworks like Django and Pyramid, Python is quite popular on the web. It is used for back-end development, so the area of web development users do not see, in other words, the server side of an app.

JavaScript is a scripting language that lets you create interactive web pages. It runs in the user’s web browser without needing any resources from the web server.

JavaScript can be used in developing both - the back-end and the front-end of the app. It is used in web dev because it is a versatile language, and it gives the tools needed to develop the components of web apps.

To summarize our introduction:

Python can be used for web development and a wide range of applications, including scientific purposes. On the other hand, JavaScript is used mainly for web development - front-end and back-end - but also for mobile app development.

Both languages are two the most popular programming languages among software developers - comparing them head to head is not going to give you a straight answer about which language is better. But it is good to know which language performs specific tasks better or does things that the other language simply cannot.

Python vs. JavaScript

Let’s talk about the key differences between Python and JavaScript in terms of:

Performance & Speed

Usually, when comparing languages ​​in terms of performance and speed, they face the same task. However, since Python and JavaScript are two different technologies designed for different purposes, we can state that JavaScript is the leader on the front-end. At the same time, Python reigns in the back-end due to horizontal scaling.

We can explain it better based on the Pinterest example.

When analyzing the performance component of Python vs. JavaScript - JS is the definite winner.

Python has to process requests in a single flow, while applications based on Node.js have advanced multithreading. JavaScript's initial purpose of creating was to make it fast on the web.

There are always two sides to every situation - apps that require dynamic and real-time interactions are built on JavaScript (users do not like to wait!), and the same can be said about websites and ERP apps since JS works on both domains.

So, for example, Facebook, which generates an enormous amount of data, is more likely to use JS, so the users do not have to wait.

The other side is that processing data and solving machine learning problems is better to choose Python. Python is easy to read and use, even in the complicated situations of handling CPU or using GPUs.

Python might take longer to respond, but there are possibilities for Python to perform quickly if you optimize it accordingly - starting from C programming language with the help of NumPy or by using Cython.

Procedural Programming

Python and JavaScript have adopted a multi-paradigm methodology, encouraging more than one programming paradigm.

It means that Python provides support for object-oriented programming, functional programming, imperative programming, and procedural programming.

JavaScript does the same with one exception - JS does not have as many aspects of a language for procedural programming as Python.


Scalability is considered a significant factor when comparing these two languages - it contributes to the strengths of the languages when managing a massive amount of users and storing a huge amount of data.

Node.js has the already mentioned multithreading. Thanks to this feature, it can improve scalability by increasing the number of threads.

Python uses Global Interpreter Lock (GIL). GIL makes only one thread running at a time. What goes with it is that using multiple processors with threads is harder but not impossible. Python is trying to overcome this issue, and developers can use a multiprocessing library. It offers them functionality for distributing work between multiple processes using multiple CPU cores.

REPL (Read-Eval-Print-Loop)

Developers automatically have access to REPL with the installation of Python on their system.

JavaScript does not come with an in-built REPL because the code mainly runs on the browser. Nevertheless, it is possible to have it by downloading Node.js.


There are two types of data - mutable and immutable. In Python, everything is treated as an object, and Python supports both - mutable and immutable objects.

For instance, the set is a mutable data type, but custom classes are also mutable, plus list, byte array, and dict. Immutable objects such as tuple, string, int, and float also exist.

The definition of mutability does not exist in JavaScript - data can be reference type or primitive type:

  • Reference type means that objects are constituted by multiple properties stored as a reference.

  • Primitive type - data is neither an object nor has a method.

All primitive values in JS are immutable, but objects and arrays are mutable.

Function Arguments

Python raises an exception if a function is called with incorrect parameters. It accepts some additional parameters with the special syntax “*args”.

Whereas JavaScript does not care whether a function is called with exact parameters. Because any missing parameter gets a value as “undefined” by default. If there are any extra arguments - they are treated as special arguments.


Both languages support inheritance. The difference lies in their types.

JS is not considered as a pure object-oriented language because it only supports inheritance by relying on a prototype-based inheritance model.

Python, on the other hand, uses a class-based inheritance model.

An important distinction is also the fact that Python does not have a way to inherit from instances, and JS has.

Strongly-typed vs. Weakly-typed

Python is strongly typed, so there is no implicit conversion between types, while JavaScript is weakly-typed, so conversions between unrelated types are made implicitly.

Libraries and Modules

Python comes with many included modules and libraries. Thanks to this, developers can easily perform tasks for all sorts of fields, e.g., data analytics, machine learning, scientific computing, etc.

JS does not have as many modules as Python, but it does include the date, math, JSON, and regex. In addition, you can use extra functionality through the host environment.

When to choose Python and when to use JavaScript

JavaScript excels at adding interactive behavior to web pages. It is a great choice for creating web and mobile applications. JavaScript is the only programming language native to web browsers and provides developers with many frameworks (e.g., React, Angular, Vue).

It can also build web servers and develop server applications, thanks to Node.js for supporting the back-end side of the project.

However, Python is the best choice for machine learning, artificial intelligence, data visualization, and data analytics. Regarding web development, Python is powerful in the back-end and has several libraries and frameworks like Flask, Django, or Pyramid.

For quite some time, Python was considered a language not suitable for mobile development. It was true in the past. The IT world is changing rapidly, and there are modern solutions that have been developed and changed the way we can see Python.

Python can be used to create several types of programs for multiple platforms. Since Python is cross-platform, it allows the developers to use GUI frameworks like BeeWare and Kivy and transform the code into versions that work not only with iOS and Android but with other platforms as well. As a result, developers do not need to work on two entirely different versions of the same app based on different programming languages.

Summarizing the above:

Is Python the language for mobile development? Yes.

Is it the most suitable option? Probably not, despite the modern solutions available. Python is not iOS or Android native, so many developers hesitate to use it while creating a mobile app. It may cause slow deployment or make it more complex.

Popular websites such as Google, YouTube, Facebook, Amazon, Twitter, LinkedIn, and Wikipedia were built using JavaScript. At the same time, many top tech companies use Python for their back-end development. These companies include giants like Google, Instagram, Uber, Spotify, Netflix, etc.


If you are looking for the answer to the question of which language is better - Python or JavaScript - we are sorry, but there is no simple answer.

With Python, you can basically do almost everything that you can do with JavaScript. Both share a common element, and structurally, there are some similarities, but they bring different expertise to programming.

If you are looking for a modern yet established language, your projects revolve around start-up environment and web development - choose JavaScript. However, if robust and minimalist languages, experimental fields, and working on AI, MI is something that you are into, then you should definitely go for Python.

In general, why not both? They have important differences, but you can use one or another depending on your needs since both have the same basic elements. Every programming language serves a different purpose. The best solution is to make the most out of both languages and combine them using, for example, Python for the back-end and JavaScript for the front-end.

Sunscrapers Team

Sunscrapers empowers visionary leaders to ride the wave of the digital transformation with solutions that generate tangible business results. Thanks to agile and lean startup methods, we deliver high-quality software at top speed and efficiency.




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