It's not that easy to choose between two incredible and widely popular programming languages. Hopefully, this article will clear out any doubt regarding the main differences between Python and JavaScript. More importantly, we will explain which is the most appropriate language regarding the different purposes of every project. Curious to find out?

Table of Contents

Introduction to JavaScript
Introduction to Python
Python vs JavaScript: key differences
    ➤  Popularity
    ➤  Performance
    ➤  Scalability
    ➤  Mutable vs. Immutable
    ➤  Inheritance
    ➤  REPL
    ➤  Strongly-typed vs Weakly-typed
    ➤  Multiparadigm
    ➤  Function Arguments
    ➤  Libraries and Modules
Python vs JavaScript: when to use?
Conclusion

Introduction to JavaScript

JavaScript (JS) is the most popular programming language worldwide. It is considered a high-level language and is distinguished for its dynamic typing and just-in-time (JIT) compiler. Moreover, JavaScript is also a multi-paradigm language due to its capability to support different types of programming, such as functional, imperative, and event-driven programming.

One commonly debated question is whether or not JavaScript is an object-oriented programming language. Well, as explained in our JavaScript vs. TypeScript post: "Upon JavaScript's release of ES6, the concept of classes was indeed introduced. However, this is a syntax feature for JavaScript's prototypal inheritance. JS is prototype-based, not class-based. Hence, JavaScript is not considered a pure object-oriented programming language". Nonetheless, it does have the ability to support some object-oriented principles, such as encapsulation and polymorphism.

One of the reasons why JavaScript is so known comes from its ability to handle both backend and frontend development, creating interactive and dynamic web pages. Overall, it is a very versatile language that provides developers with multiple libraries and frameworks to excel at web development.

Introduction to Python

Python is a dynamically typed programming language. Hence, it executes type checking during runtime. It was initially developed by Guido van Rossum and introduced in 1991. It is currently among the most popular programming languages globally due to its readability, easiness to use, and ability to be used in various fields, from data science to machine learning, computer vision, artificial intelligence, web development, and so on.

As we mentioned in our article Python vs. Java, Python is considered a "very powerful and clear object-oriented programming language". Another great plus is that users can download and use it for free. Since it is available under the GNU General Public License (GPL), it can be freely redistributed or modified.

Python vs JavaScript: key differences

The first thing we should take into consideration is that JavaScript is a scripting language, and each command or line is interpreted (not compiled) one by one by the web browser throughout the runtime. Hence, JavaScript follows a client-side implementation. However, it also has engines that provide server-side implementations. In fact, the popularity of Node.js resulted in the consequent growth of JavaScript as a server-side technology. Nevertheless, it is often considered not ideal for large and complex applications since it becomes harder to maintain and reuse code as it grows.

In comparison, as a general-purpose programming language, Python can be used as a scripting language. In other words, Python is not necessarily just a scripting language but rather a general-purpose programming language that can also work well as a scripting language. Moreover, Python is an object-oriented programming language, mainly used as a server-side language. Its commands are compiled to bytecode during runtime, and afterward, an interpreter executes the byte code. It can also be used as a front-end language, although it is less common.

Therefore, before moving on to the key differences between Python vs JavaScript, it is important to highlight how one language does not necessarily replace the other. In fact, Python and JavaScript can complement each other and make the most out of their strengths by perhaps using Python to work on the server-side and JavaScript on the client-side. For instance, Instagram uses Python (and Django) for the back-end; and native programming languages and JavaScript for the interface.

Popularity

According to The 2020 State of the Octoverse, JavaScript has been the most popular programming language for many years, having an undeniably high-grade reputation among developers. However, Python is definitely challenging the throne. It has had an impressive popularity growth over the years (especially since 2018), mainly due to creating great web development frameworks (such as Django) and being the go-to language for machine learning and data science.

Currently, according to Stack Overflow Developer Survey 2020, JavaScript (67.7%) has maintained its position as the number one most commonly used language, and Python is still a bit behind (44.1%). Nonetheless, if we look at the TIOBE Index for July 2021, Python is in third place regarding programming language popularity, and JavaScript comes in seventh. Last but not least, let's also consider Github's PYPL - Popularity of Programming Language, which indicates that Python is the most searched popular language, and JavaScript the third.

Performance

One of JavaScript's main purposes was to be fast on the web. Compared with Python, Node.js has a faster performance thanks to its advanced multithreading ability. Unlike Python, which has to process requests in a single flow.

On the one hand, applications that require dynamic and real-time interactions are often built on JavaScript to avoid making users wait. On the other hand, to process vast amounts of data and to solve a specific issue regarding machine learning, Python is the most suitable option. It stands out for its readability and easiness of use, even when handling CPU-intensive situations or complex computation using GPUs.

Moreover, even though Python might take longer to respond, there are a couple of ways to improve its performance by benefiting from the C programming language with NumPy and by using Cython. Cython is a compiler that allows developers to create fast C modules, speeding up Python's code execution.

Scalability

Python uses Global Interpreter Lock (GIL), which consequently makes concurrent programming more difficult. GIL ensures that only one thread runs at a time, making it harder (not to say impossible) to use multiple processors with threads. To overcome this issue, Python enables developers to use the multiprocessing library, which offers functionality for distributing work between multiple processes by using multiple CPU cores.

Multithreading is the most suitable solution for an application to be scalable, and Node.js - which is implemented on JavaScript - has it. Thanks to multithreading, it is possible to improve scalability by increasing the number of threads.

Mutable vs. Immutable

A mutable item is able to modify its states or content. Contrarily, immutable items cannot.

In Python, everything is treated as an object. Therefore, once an object is initiated, a unique object ID is attributed, and the object's type is defined at runtime. When the type is set, it cannot change. However, the object's state can be changed if it is mutable. Python supports both mutable and immutable concepts. Usually, custom classes are mutable, as well as the following objects: list, set, byte array, and dict. However, Python also has immutable objects, such as tuple, string, int, and float.

The data specified to a JavaScript variable can be:

• Reference type: objects constituted by multiple properties, which are stored as a reference. When a reference has attributed a value from one variable to another, then the value stored in the variable is likewise copied into the new variable.
• Primitive type: data that is neither an object nor has methods, including string, numbers, boolean, symbol, null, and undefined.

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

Inheritance

Inheritance is one of the four core principles of object-oriented programming languages. This concept consists of one class inheriting the attributes and methods from another class, the parent class.

As mentioned, JS is not considered a pure object-oriented language because even though it introduced the concept of classes, this language only supports inheritance by relying on a prototype-based inheritance model. Contrarily, as an OOP language, Python uses a class-based inheritance model.

REPL

With Python, developers automatically have REPL (Read-Eval-Print-Loop) installed on the system; it is a built-in technique. In comparison, JavaScript does not come with REPL since its code mainly runs on the browser. However, it is possible to have this technique in JavaScript if developers install Node.js.

Strongly-typed vs Weakly-typed

On the one hand, Python is strongly typed, hence no implicit conversions between types. On the other hand, JavaScript is weakly typed, meaning that conversions between unrelated types are made implicitly.

Multiparadigm

Both Python and JavaScript support various programming paradigms. The first supports object-oriented programming, functional programming, imperative programming, and procedural programming. In turn, JavaScript supports exactly the same paradigms, except for procedural programming.

Function Arguments

If a function is called with incorrect parameters, Python establishes an exception. Plus, the programming language also admits some additional parameter passing syntax.

If functions are called with incorrect parameters in JavaScript, then their value is automatically considered "undefined". Hence, JS is not as worried as Python about the exact parameters. Further, in case of any additional arguments, these will be treated by JS as special arguments.

Libraries and Modules

Python is a "batteries-included" programming language. It comes with many included modules and libraries, allowing developers to easily perform various tasks for scientific computing, data analytics, machine learning, etc.

JavaScript does not have as many ready-to-use modules as Python, but it does include date, math, JSON, and regexp. Moreover, additional functionality is available for JavaScript through the host environment.

Python vs JavaScript: comparison table

Python vs JavaScript: when to use?

As explained, Python and JavaScript can definitely complement each other in software development projects. However, in some particular applications, one might be more suitable than the other.

On the one hand, JavaScript excels at adding interactive behavior to web pages, allowing users to interact easily. Plus, it is a great choice for creating web and mobile applications. It is the only programming language native to the web browser and provides developers with several frameworks (e.g., React, Angular, and Vue).

Nonetheless, it can also build web servers and develop server applications by relying on Node.js for the back-end infrastructure. In that case, two of the most commonly used frameworks are Express and Meteor.js. Therefore, for developers that wish to use JavaScript for server-side implementations, JS has the tools! Yet, it was only possible due to the development of Node.js (initially released in 2009); until then, JavaScript's primary focus was on the client-side.

On the other hand, Python is the right choice for machine learning, artificial intelligence, data visualization, and data analytics. Regarding web development, Python is very powerful in the back-end and has several great libraries and frameworks, such as Flask,Django, and Pyramid.

Moreover, there's this general idea that Python is not very suitable for mobile development. For a long time, that might have been true, but currently, we should probably not misjudge it so quickly without considering the modern solutions that have been developed.

As a general-purpose and cross-platform programming language, Python can be used to create several types of programs for multiple platforms. Being cross-platform allows Python developers to use GUI frameworks such as BeeWare and Kivy to transform Python's code into the respective versions that work with iOS, Android, or other platforms. Therefore, developers do not need to work on two entirely different application versions based on different programming languages. Further, it is also not required to develop separate apps one by one for each platform.

In sum, can Python be used for mobile development? Yes, for sure. Is it the most suitable option? Well, despite the creation of modern solutions, for many developers, Python is still not the number one choice in mobile development, partly because it is not iOS or Android native, which can consequently slow deployment or make it more complex. Nonetheless, JavaScript or even Kotlin are great options for mobile development as well.

Further, it is also important to consider each developer's preference for the programming languages in question. If a developer is very comfortable with Python and likes to explore this language's versatility, then there's nothing wrong with going for Python in mobile development.

Conclusion

Python and JavaScript did not become two of the most popular languages by luck. Over the years, they have developed libraries and frameworks that are extremely effective and further gathered all the crucial requirements to help developers excel at software development.

Despite their differences, there is not really a wrong option when choosing between Python and JavaScript. In fact, we recommend developers to make the most out of both languages by combining them, using perhaps Python for the back-end and JavaScript for the front-end.

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