JavaScript Comments: Why Writing Them is a Superpower for Developers

JavaScript Comments: The Art of Writing for Humans, Not Just Machines
We've all been there. It's 2 AM. The coffee has run out, but the code is finally flowing. You’re weaving JavaScript logic like a digital wizard, solving problems that felt impossible just hours before. In that moment of pure flow, everything makes perfect sense. The variable dttlP? Obviously discountedTotalPrice. The complex function that handles API calls, data transformation, and error handling? A work of art. You promise yourself you’ll clean it up tomorrow.

Then, tomorrow becomes next week. A bug report comes in. You open the file, and a cold shiver runs down your spine. You stare at the screen, squinting at the lines of code you authored. It feels like you're trying to read a novel in a language you only vaguely remember.

"Who wrote this?" you think, before the horrifying realization dawns: It was me.

This universal experience among developers is precisely why learning to write effective JavaScript comments is not a mundane task—it’s a superpower. It's the difference between being a coder and being a craftsman. At CoderCrafter, we don't just teach you how to make code work; we teach you how to build software that lasts, and it all starts with practices like this.

Why Bother? The Comment as a Love Letter to the Future
The JavaScript engine completely ignores comments. So why waste the keystrokes? Because software is never just about instructing a machine; it's about communicating with other people, and most importantly, with your future self.

Comments are love letters, time capsules, and breadcrumbs all rolled into one. They are for:

Future You: The most important audience. The you that hasn't had three cups of coffee and forgotten the intricate problem you just solved.

Your Teammates: In a collaborative environment, your code is a conversation. Comments are your way of explaining your thought process, your assumptions, and your intent, making code reviews and collaboration seamless.

Other Developers: If you ever build a library, framework, or open-source project, comments are the first step toward great documentation. They help others understand how to use your creation effectively.

The Toolkit: Your Two Best Friends in JavaScript
JavaScript provides you with two simple but powerful tools for commenting.

1. The Single-Line Comment (//): The Quick Nudge The humble // is your go-to for brief, inline explanations. It’s perfect for adding a quick note on the same line or the line above a piece of code.

Example:

javascript
// Initialize an array to hold our user objects
let userList = [];

// Make API call to fetch initial data
fetchUserData();

const price = quantity * unitPrice; // Calculate gross price before discounts
Think of it as a sticky note—short, direct, and right where you need it.

1. The Multi-Line Comment (/* ... /): The Detailed Blueprint When you need more than a quick note, the / ... */ syntax lets you write longer explanations that span multiple lines. This is ideal for describing the purpose of a function, a complex algorithm, or a module at the top of a file.

Example:

javascript
/*

• @function calculateCompoundInterest
• @desc Calculates the future value of an investment based on compound interest.
• {number} principal - The initial amount of money.
• {number} rate - The annual interest rate (in decimal form, e.g., 5% = 0.05).
• {number} time - The time the money is invested for (in years).
• {number} compoundFrequency - The number of times interest is compounded per year.
• @returns {number} The total amount after compound interest. */ function calculateCompoundInterest(principal, rate, time, compoundFrequency) { const amount = principal * Math.pow(1 + rate / compoundFrequency, compoundFrequency * time); return parseFloat(amount.toFixed(2)); } This block doesn't just say what the function does; it explains how to use it, what each parameter means, and what to expect in return. This is the foundation of self-documenting code.

Beyond Syntax: The Philosophy of a Good Comment
Anyone can learn the syntax. The true skill lies in knowing what to comment and how. The golden rule is this: Don't explain the "what." Explain the "why."

The code itself already shows what is happening. Your comments should reveal the reasoning that the code can't.

Bad Comments (The "What"):
javascript
let x = 10; // set x to 10
for (let i = 0; i < 10; i++) { // loop from 0 to 9
x += i; // add i to x
}
// Bad: These comments are just noise. They add zero value and clutter the code.
Good Comments (The "Why"):
javascript
// We're initializing with a base value of 10 to account for the initial setup fee
let totalCost = 10;

// Process each of the first 10 subscription tiers and accumulate their cost
// Skip tier 0 as it's a free plan, hence starting from i=1
for (let i = 1; i < 10; i++) {
totalCost += getTierCost(i);
}
// Good: This explains the business logic and reasoning behind the code.
Other Great Reasons to Comment:
TODO Notes: Acknowledging incomplete sections.

javascript
// TODO: Refactor this to use a more efficient sorting algorithm for large datasets
FIXME Highlights: Marking known bugs or problematic code.

javascript
// FIXME: This API endpoint times out under heavy load; need to add a retry mechanism
Documenting Unusual Workarounds: Sometimes, you have to write weird code to fix a specific bug.

javascript
// Using setTimeout to delay execution until after the DOM update cycle is complete
// This is a workaround for the CSS transition bug in Firefox
setTimeout(() => {
element.classList.add('highlight');
}, 0);
The Counter-Argument: Can Comments Be Bad?
Yes. Poor comments can be worse than no comments. The biggest sin is writing comments that lie. When code is updated but its comments are not, it creates confusion and misinformation. This is why your primary goal should always be to write clear, self-explanatory code.

Choose descriptive variable and function names. Break complex functions into smaller, well-named ones. Often, if you feel you need a comment, you might need to refactor your code instead.

Instead of this:

javascript
// Function to process data
function p(d) {
// Check if d is valid
if (d && d.a && d.a.b > 0) {
// do stuff
return d.a.b * 1.1;
}
}
Write this:

javascript
function calculateFinalPrice(orderData) {
const hasValidOrder = orderData?.payment?.subtotal > 0;

if (hasValidOrder) {
const taxRate = 0.1;
return orderData.payment.subtotal * (1 + taxRate);
}
}
The second version uses clear naming and optional chaining (?.), making most comments unnecessary.

From Theory to Practice: Building Habits for a Successful Career
Understanding comments is a fundamental pillar of professional software development. It’s a sign of maturity, empathy for your colleagues, and pride in your work. These aren't just minor tips; they are the habits that define senior developers and effective team players.

This meticulous attention to detail and focus on clean, maintainable, and collaborative code is what we bake into every course at CoderCrafter. Whether you're embarking on your journey with our Full Stack Development course or diving deep into the modern tech stack with our MERN Stack Development program, you'll learn to build real-world applications the right way.

We don’t just want you to write code. We want you to build software that stands the test of time, and that starts by writing for your second-most important audience: humans.

Ready to transform your coding from a solo act into a symphony of collaboration? Visit CoderCrafter.in today to explore our courses and enroll. Your future self—and your future teammates—will thank you.