The Art of Maintainable Code: What I Wish I'd Known Years Ago

I want to tell you a short, true, and embarrassing story.

Early in my career, I wrote a "brilliant" piece of code. It was a single, beautiful line of JavaScript that used multiple ternaries, map, and reduce to transform a complex data structure. I was so proud. It was clever. It was dense. It was smart.

Six months later, a bug report came in related to that feature. I opened the file, looked at my "brilliant" line of code, and had absolutely no idea what it did.

It took me two hours to debug a single line I, myself, had written. This was my "Aha!" moment. I realized the most important, painful lesson in software engineering: Clarity is more important than cleverness.

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🧠 The Most Important Rule: Code is Read More Than It Is Written

We developers often think our job is to "write code." It's not. Our job is to build and maintain systems. Writing the code is just the first, smallest step.

For the rest of its life, that code will be read, debugged, extended, and refactored by dozens of other developers—including your future self, who has forgotten all the "clever" tricks you used.

Your goal as a professional is not to show how smart you are. Your goal is to write code that is so simple, so clear, that its intent is obvious at a glance. Maintainable code is an act of empathy for the next person.

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🏷️ 1. Naming is 90% of the Battle

If you need a comment to explain what a variable does, you haven't failed at commenting. You've failed at naming. Good naming is the foundation of readable code.

• Bad: let data; (What data? A string? An array? An object?)

• Good: let activeUsers = []; (Ah. It's an array. It's for users. They are active.)

• Bad: function process(arr) { ... } (Process what? How?)

• Good: function fetchUsersByTenantId(tenantId) { ... } (Perfect. I know what it does, what it needs, and what it likely returns without even reading its contents.)

Spend the extra 30 seconds to find the right name. It will save hours of debugging later.

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📦 2. Your Functions are Lying to You (The Single Responsibility Principle)

A common mistake is creating "utility" functions that do everything. I once saw a function called handleUserLogin(). Its 200 lines of code did the following:

1. Validate the form input.
2. Send the credentials to an API.
3. Parse the API response.
4. Save the auth token to localStorage.
5. Set a cookie.
6. Fetch the user's profile data.
7. Update the Redux store.
8. Redirect the user to the dashboard.

What happens when you need to change only the cookie-setting logic? You have to wade into this "god function" and pray you don't break the other seven things it's doing.

The Fix: A function should do one thing. Its name should describe that one thing. If your function name includes the word "and" or "or", it's a huge red flag that it's doing too much.

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🪄 3. Avoid "Magic" and Premature Abstraction

Abstraction is a powerful tool, but when used poorly, it's worse than duplication. I call this "The DRY Trap."

Beginners see two slightly similar blocks of code and immediately write a "reusable" function to handle both. The result is often a monstrous function with six boolean flags as parameters (doThis, butNotThat, useSpecialCase).

The Rule: Duplication is far cheaper than the wrong abstraction.

• First time you write it: Just write the code.
• Second time you write it: Copy, paste, and adapt it. Start to feel the pain.
• Third time you write it: You now have three examples. You finally understand the actual pattern. Now, and only now, are you allowed to refactor and create a clean, correct abstraction.

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💬 4. Write Comments That Explain Why, Not What

Your code should always explain the what. A good comment explains the why.

• Bad Comment: // Increment i by 1 (Yes, I can see that... i++)

• Good Comment: // We must increment i here to skip the header row, which is processed separately. (This is information the code cannot tell me.)

• Bad Comment: // A terrible, temporary hack

• Good Comment: // HACK: The external widget-v3 API times out on payloads > 1MB. // We must manually batch these requests until they fix it. // See JIRA-452 for details.

A good comment tells the story, explains the business or technical constraints, and gives the next developer the context they need.

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🚀 Conclusion

Writing maintainable code isn't a "nice-to-have." It is a core, non-negotiable part of being a professional engineer.

It's the difference between a codebase that rots and becomes a "legacy" nightmare, and one that can adapt, grow, and continue to deliver value for years.

Clever code impresses your junior-self. Clear, simple, and maintainable code impresses your senior mentors and builds a foundation for a scalable team.