JavaScript is like Python

This article presents a comparison between the syntax and fundamental programming constructs of JavaScript and Python. It aims to highlight similarities in how basic programming concepts are implemented across these two popular programming languages.

While both languages share many commonalities, making it easier for developers to switch between them or understand the other's code, there are also distinct syntactical and operational differences that one should be aware of.

It's important to approach this comparison with a light-hearted perspective and not to overemphasize the likeness or differences between JavaScript and Python. The intention is not to declare one language superior to the other but to provide a resource that can help coders who are familiar with Python to understand and transition to JavaScript more easily.

Hello World

JavaScript

// In codeguppy.com environment
println('Hello, World');

// Outside codeguppy.com
console.log('Hello, World');

Python

print('Hello, World')

Variables and Constants

JavaScript

let myVariable = 100;

const MYCONSTANT = 3.14159;

Python

myVariable = 100

MYCONSTANT = 3.14159

String Interpolation

JavaScript

let a = 100;
let b = 200;

println(`Sum of ${a} and ${b} is ${a + b}`);

Python

a = 100
b = 200

print(f'Sum of {a} and {b} is {a + b}')

If Expression / Statement

JavaScript

let age = 18;

if (age < 13) 
{
    println("Child");
} 
else if (age < 20) 
{
    println("Teenager");
} 
else 
{
    println("Adult");
}

Python

age = 18

if age < 13:
    print("Child")
elif age < 20:
    print("Teenager")
else:
    print("Adult")

Conditionals

JavaScript

let age = 20;
let message = age >= 18 ? "Can vote" : "Cannot vote";
println(message);  // Output: Can vote

Python

age = 20
message = "Can vote" if age >= 18 else "Cannot vote"
print(message)  # Output: Can vote

Arrays

JavaScript

// Creating an array
let myArray = [1, 2, 3, 4, 5];

// Accessing elements
println(myArray[0]);  // Access the first element: 1
println(myArray[3]);  // Access the fourth element: 4

// Modifying an element
myArray[2] = 30;  // Change the third element from 3 to 30

// Adding a new element
myArray.push(6);  // Add a new element to the end

Python

# Creating a list to represent an array
my_array = [1, 2, 3, 4, 5]

# Accessing elements
print(my_array[0])  # Access the first element: 1
print(my_array[3])  # Access the fourth element: 4

# Modifying an element
my_array[2] = 30  # Change the third element from 3 to 30

# Adding a new element
my_array.append(6)  # Add a new element to the end

ForEach

JavaScript

let fruits = ["apple", "banana", "cherry", "date"];

for(let fruit of fruits)
    println(fruit);

Python

fruits = ["apple", "banana", "cherry", "date"]

for fruit in fruits:
    print(fruit)

Dictionaries

JavaScript

// Creating a dictionary
fruit_prices = {
    apple: 0.65,
    banana: 0.35,
    cherry: 0.85
};

// Accessing a value by key
println(fruit_prices["apple"]);  // Output: 0.65

Python

# Creating a dictionary
fruit_prices = {
    "apple": 0.65,
    "banana": 0.35,
    "cherry": 0.85
}

# Accessing a value by key
print(fruit_prices["apple"])  # Output: 0.65

Functions

JavaScript

function addNumbers(a, b) 
{
    return a + b;
}

let result = addNumbers(100, 200);
println("The sum is: ", result);

Python

def add_numbers(a, b):
    return a + b

result = add_numbers(100, 200)
print("The sum is: ", result)

Tuple Return

JavaScript

function getCircleProperties(radius) 
{
    const area = Math.PI * radius ** 2;
    const circumference = 2 * Math.PI * radius;

    return [area, circumference];  // Return as an array
}

// Using the function
const [area, circumference] = getCircleProperties(5);

println(`The area of the circle is: ${area}`);
println(`The circumference of the circle is: ${circumference}`);

Python

import math

def getCircleProperties(radius):
    """Calculate and return the area and circumference of a circle."""
    area = math.pi * radius**2
    circumference = 2 * math.pi * radius
    return (area, circumference)

# Using the function
radius = 5
area, circumference = getCircleProperties(radius)

print(f"The area of the circle is: {area}")
print(f"The circumference of the circle is: {circumference}")

Variable number of arguments

JavaScript

function sumNumbers(...args) 
{
    let sum = 0;
    for(let i of args)
        sum += i;
    return sum;
}

println(sumNumbers(1, 2, 3));
println(sumNumbers(100, 200));

Python

def sum_numbers(*args):
    sum = 0
    for i in args:
        sum += i
    return sum

print(sum_numbers(1, 2, 3))
print(sum_numbers(100, 200))

Lambdas

JavaScript

const numbers = [1, 2, 3, 4, 5];

// Use map to apply a function to all elements of the array
const squaredNumbers = numbers.map(x => x ** 2);

println(squaredNumbers);  // Output: [1, 4, 9, 16, 25]

Python

numbers = [1, 2, 3, 4, 5]

# Use map to apply a function to all elements of the list
squared_numbers = map(lambda x: x**2, numbers)

# Convert map object to a list to print the results
squared_numbers_list = list(squared_numbers)

print(squared_numbers_list)  # Output: [1, 4, 9, 16, 25]

Classes

JavaScript

class Book 
{
    constructor(title, author, pages) 
    {
        this.title = title;
        this.author = author;
        this.pages = pages;
    }
    
    describeBook() 
    {
        println(`Book Title: ${this.title}`);
        println(`Author: ${this.author}`);
        println(`Number of Pages: ${this.pages}`);
    }
}

Python

class Book:
    def __init__(self, title, author, pages):
        self.title = title
        self.author = author
        self.pages = pages
    
    def describe_book(self):
        print(f"Book Title: {self.title}")
        print(f"Author: {self.author}")
        print(f"Number of Pages: {self.pages}")

Usage of classes

JavaScript

// Creating an instance of the Book class
// This is actually a real book (see Curriculum section for more info)
const myBook = new Book("Illustrated JavaScript", "Marian Veteanu", 684);
myBook.describeBook();

Python

# Creating an instance of the Book class
# This is actually a real book (see Curriculum section for more info)
my_book = Book("Illustrated JavaScript", "Marian Veteanu", 684)
my_book.describe_book()

Conclusion

We encourage you to get involved in refining this comparison. Your contributions, whether they are corrections, enhancements, or new additions, are highly valued. By collaborating, we can create a more accurate and comprehensive guide that benefits all developers interested in learning about JavaScript and Python.

Credits

This article was influenced by similar comparisons between other programming languages. Please note that clicking on the following links will take you outside codeguppy.com environment.

Kotlin is like C# https://ttu.github.io/kotlin-is-like-csharp/
Kotlin is like TypeScript https://gi-no.github.io/kotlin-is-like-typescript/
Swift is like Kotlin https://nilhcem.com/swift-is-like-kotlin/
Swift is like Go http://repo.tiye.me/jiyinyiyong/swift-is-like-go/
Swift is like Scala https://leverich.github.io/swiftislikescala/

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JavaScript is like Python