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2026-01-076 min read

JS Keywords (Python Programming)

Learn JS Keywords (Python Programming) step by step with clear examples and exercises.

Why This Matters

Learn how to use JavaScript keywords correctly in your Python code to avoid common mistakes and improve your programming skills.

Why This Matters

JavaScript keywords are essential for writing clean, efficient, and maintainable code. Understanding how they work can help you write more effective Python programs that mimic the behavior of JavaScript. This lesson will provide you with a full guide to using JavaScript keywords in Python, along with practical examples, common mistakes, and practice questions.

Prerequisites

To get the most out of this lesson, you should have a basic understanding of:

  • Python syntax and data structures (variables, functions, loops, conditionals)
  • The differences between JavaScript and Python

Core Concept

Python has its own set of keywords, but it also supports using JavaScript keywords as identifiers. This can be useful when working with libraries or frameworks that use a mix of both languages. However, it's important to understand the differences between JavaScript and Python keywords to avoid confusion and errors.

JavaScript Keywords in Python

JavaScript keywords are case-sensitive, while Python is not. In Python, you can use JavaScript keywords as identifiers by following these rules:

  1. Use the keyword exactly as it appears in JavaScript (case-sensitive).
  2. Do not use Python reserved words as identifiers.
  3. If a JavaScript keyword is also a Python reserved word, you cannot use it as an identifier in Python.

Here's a list of some common JavaScript keywords and their equivalent Python behavior:

JavaScript Keywords in Python

break = None # Not a Python reserved word; can be used as an identifier

case = None # Not a Python reserved word; can be used as an identifier

catch = None # Not a Python reserved word; can be used as an identifier

class = None # Python keyword, cannot be used as an identifier

const = None # JavaScript keyword, cannot be used as an identifier in Python

continue = None # Can be used as an identifier, but it's a built-in function in Python

debugger = None # JavaScript keyword, cannot be used as an identifier in Python

default = None # Not a JavaScript reserved word; can be used as an identifier

delete = None # JavaScript keyword, cannot be used as an identifier in Python

do = None # Not a JavaScript reserved word; can be used as an identifier

else = None # Python keyword, can be used as an identifier

export = None # JavaScript keyword, cannot be used as an identifier in Python

extends = None # JavaScript keyword, cannot be used as an identifier in Python

finally = None # Python keyword, can be used as an identifier

for = None # Python keyword, can be used as an identifier

function = None # JavaScript keyword, cannot be used as an identifier in Python

if = None # Python keyword, can be used as an identifier

import = None # Python keyword, can be used as an identifier

in = None # Python keyword, can be used as an identifier

instanceof = None # JavaScript keyword, cannot be used as an identifier in Python

new = None # JavaScript keyword, cannot be used as an identifier in Python

return = None # Can be used as an identifier, but it's a built-in function in Python

super = None # Python keyword, can be used as an identifier

switch = None # Not a JavaScript reserved word; can be used as an identifier

this = None # JavaScript keyword, cannot be used as an identifier in Python

throw = None # JavaScript keyword, cannot be used as an identifier in Python

try = None # Python keyword, can be used as an identifier

typeof = None # JavaScript keyword, cannot be used as an identifier in Python

var = None # JavaScript keyword, cannot be used as an identifier in Python

void = None # JavaScript keyword, cannot be used as an identifier in Python

while = None # Python keyword, can be used as an identifier

with = None # Python keyword, can be used as an identifier

yield = None # Python keyword, can be used as a generator function


### Common Mistakes

1. Using JavaScript keywords that are also Python reserved words:

class = 5 # This will cause a syntax error because 'class' is a Python reserved word

2. Forgetting to use parentheses when calling built-in functions that have the same name as JavaScript keywords:

for i in range(10): # Correct usage

for (i in range(10)): # Incorrect usage; Python uses parentheses for function calls

3. Using JavaScript keywords as identifiers when they are not supported:

debugger = 5 # This will cause a syntax error because 'debugger' is a JavaScript keyword and cannot be used as an identifier in Python

Worked Example

Let's create a simple Python program that uses the JavaScript for loop to iterate over a list:

A simple Python program using the JavaScript 'for' loop

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

for i in numbers:

print(i)


In this example, we use the `for` keyword as an identifier, which is allowed in Python. The program iterates over the list of numbers and prints each one to the console.

Common Mistakes

  1. Using JavaScript keywords as variable names when they are not supported:
const = 5 # This will cause a syntax error because 'const' is a JavaScript keyword and cannot be used as an identifier in Python
  1. Confusing Python and JavaScript syntax when using JavaScript keywords:
for i in range(10):
print(i) # Incorrect usage; Python uses indentation to define blocks, not curly braces

Correct usage with curly braces:

for i in range(10):
print(i)

Practice Questions

  1. What is the difference between using JavaScript keywords as identifiers in Python and using Python reserved words as identifiers?
  2. Which of the following JavaScript keywords can be used as an identifier in Python without any issues: break, case, or class?
  3. Write a Python program that uses the JavaScript for loop to iterate over a list of names and print each one on a new line.
  4. What will happen if you try to use the debugger keyword as an identifier in Python?
  5. How would you handle a situation where you need to use both Python and JavaScript keywords as identifiers in the same script?

FAQ

  1. Can I use JavaScript keywords as variable names in Python?
  • Not all JavaScript keywords can be used as identifiers in Python. Some are reserved words, while others have special meaning or are not supported.
  1. Why can't I use the debugger keyword as an identifier in Python?
  • The debugger keyword is a JavaScript-specific command that triggers the browser's debugging tools. It has no meaning or purpose in Python, so it cannot be used as an identifier.
  1. What should I do if I need to use both Python and JavaScript keywords as identifiers in the same script?
  • To avoid confusion and errors, it's best to stick with Python identifiers when writing Python code. If you must use JavaScript keywords, make sure they are not reserved words or have special meaning in Python.
  1. Can I use the const keyword as an identifier in Python?
  • No, the const keyword is a JavaScript-specific declaration for variables that cannot be reassigned. It has no equivalent in Python, so it cannot be used as an identifier.
  1. What happens if I try to use a JavaScript keyword that is also a Python reserved word as an identifier?
  • Using a JavaScript keyword that is also a Python reserved word as an identifier will cause a syntax error. For example:
class = 5 # This will cause a syntax error because 'class' is a Python reserved word
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