9 Clean Coding Principles Every Developer Should Follow

1. Meaningful Names

Use descriptive and self-explanatory names for variables, functions and classes. Avoid vague terms like temp or data; instead, use names like userEmail or calculateTotalPrice that convey intent clearly.

# 🚫 Bad
d = 10

# ✅ Good 
discountPercentage = 10

Clear names reduce the need for extra comments and make your code self-documenting.

2. Single Responsibility Principle (SRP)

A function should do only one thing and do it well. If a function has multiple responsibilities, break it up.

# 🚫 Bad
def processUser():
    # Gets, validates, and saves user data
    pass

# ✅ Good 
def getUserData():
    # Retrieves user data from the database
    pass
def validateUserData(user):
    # Validates the user data
    pass

Single-purpose functions are easier to test, reuse and debug.

3. Avoid Magic Numbers

Avoid hard-coded values in your code. Use named constants that describe what the value means.

# 🚫 Bad
if (loginAttempts > 5) {
    lockAccount();
}

# ✅ Good 
final int MAX_LOGIN_ATTEMPTS = 5;
if (loginAttempts > MAX_LOGIN_ATTEMPTS) {
    lockAccount();
}

4. Keep Code DRY (Don’t Repeat Yourself)

Duplicate code means duplicate bugs. Try and reuse logic where it makes sense.

# 🚫 Bad
total1 = price1 * quantity1
total2 = price2 * quantity2

# ✅ Good
def calculate_total(price, quantity):
    return price * quantity

total1 = calculate_total(price1, quantity1)
total2 = calculate_total(price2, quantity2) 

5. Avoid Deep Nesting

Flatten your code logic by using early returns or guard clauses to avoid nested if-else or loops.

# 🚫 Bad
if (user.isActive()) {
    if (user.hasPermission()) {
        processData(user);
    }
}

# ✅ Good 
if (!user.isActive()) return;
if (!user.hasPermission()) return;
processData(user);

Reduces indentation and complexity - easier to read and debug.

6. Comment Why, Not What

Comments should explain the reason behind the code, not repeat what the code is obviously doing.

# 🚫 Bad
// Call renderUI after 100ms
setTimeout(renderUI, 100);

# ✅ Good 
// We delay here to ensure all resources are loaded before rendering
setTimeout(renderUI, 100);

Why: Good comments add insight, bad comments add noise.

7. Limit Function Arguments

Too many parameters make code hard to understand. Group related data into objects or use default parameters.

# 🚫 Bad
function createUser(name, email, role, isActive, createdOn, referralCode) {
  // ...
}

# ✅ Good
function createUser({ name, email, role }) {
  // ...
}
 

Why: Functions with fewer parameters are easier to call, read and test.

8. Code Should Be Self-Explanatory

Well-written code should tell the story of what it's doing without requiring extensive comments.

# 🚫 Bad
// Check if the cart is empty and show a message
if (cart.length == 0) {
    alert("Empty");
}

# ✅ Good
if (cart.isEmpty()) {
    showEmptyCartMessage();
}

Why: Readable code is easier to work with and needs fewer explanations.

9. Keep It Simple (KISS)

Avoid over-engineering or writing clever code that’s hard to understand.

# 🚫 Bad
def add(x, y): return (lambda a, b: a + b)(x, y)

# ✅ Good 
def add(x, y):
    return x + y