From Junior to Senior: JavaScript Coding Habits

(Code That Works ≠ Good Code) ⚠️

Writing code as a junior feels a bit like this:

“I started the car, the rest doesn’t matter.” 🚗💨

As a senior, the goal changes to this:

“Anyone should be able to drive this car — and when it breaks, it should be easy to fix.” 🔧

This article explains exactly that difference.

1️⃣ Bad Code vs Good Code

“They do the same thing, but one drives you crazy” 😅

❌ Junior-Style Code

function c(a, b, d) {
  return a * b * d;
}

Why Is This Code Bad?

• c → What is this? A calculation? A spell? Magic? 🧙‍♂️
• a, b, d → Are we taking a math exam?
• In 3 months, even you won’t remember what this does

📌 Classic junior mistake:

“I understand it right now, that’s enough.”

✅ Senior-Style Code

function calculateTotalPrice(price, quantity, taxRate) {
  return price * quantity * taxRate;
}

Why Is This Code Good?

• Function name → clearly explains what it does
• Parameters → tell a story as you read
• No comments needed

🧠 Senior reflex:

If the code explains itself, you’re on the right track.

2️⃣ Clean Code: Extra Lines = Hidden Danger 💣

❌ Overcomplicated Code

function isUserActive(user) {
  if (user.isActive === true) {
    return true;
  } else {
    return false;
  }
}

What Does This Code Do?

• Checks a boolean
• But does in 5 lines what could be done in 1

What the junior thinks:

“I wrote it this way to be clear.”

What the senior thinks:

“Unnecessary lines = future bugs.”

✅ Clean Code Version

function isUserActive(user) {
  return user.isActive;
}

What Did We Gain?

• Shorter
• Clearer
• Less room for bugs

📌 Golden Rule:

Code becomes stronger by getting simpler, not longer.

3️⃣ Readability: Code Is for Humans, Not Computers 👀

❌ Hard-to-Read Code

if(x>10&&y<5&&z!==null&&z!==undefined){
doSomething();
}

While reading this code:

• Eyes squint 👁️
• Brain gets tired 🧠
• Debugging turns into a nightmare 😵

✅ Readable Code

const isXGreaterThanTen = x > 10;
const isYLessThanFive = y < 5;
const hasZValue = z != null;

if (isXGreaterThanTen && isYLessThanFive && hasZValue) {
  doSomething();
}

Why Is This Senior-Level Code?

• Each variable is a mini explanation
• You instantly see which condition fails
• Adding logs is easy

📌 Practical Tip:
If an if looks long → break it apart.

4️⃣ Debuggability: Errors Will Happen — Don’t Panic 🐞

❌ Debugging Nightmare

function getPrice(data) {
  return data.order.price.total;
}

One day this function crashes and you see:

Cannot read property 'price' of undefined

And at that moment:

“Which data? What is undefined?” 😐

✅ Debug-Friendly Code

function getPrice(data) {
  if (!data || !data.order) {
    console.error("Missing data:", data);
    return 0;
  }

  return data.order.price?.total ?? 0;
}

What Did We Do?

• Checked if the data exists
• Left a meaningful log
• Prevented crashes with optional chaining

📌 Senior habit:

Don’t hide errors — make them visible.

5️⃣ Magic Numbers: Silent Killers 🧙‍♂️

❌ Magic Number

if (score > 85) {
  grade = "A";
}

Question overload:

• Why 85?
• Who decided that?
• What if it becomes 90 tomorrow?

✅ Meaningful Constants

const MIN_SCORE_FOR_A = 85;

if (score > MIN_SCORE_FOR_A) {
  grade = "A";
}

Advantages

• Everyone understands it
• Changes are made in one place
• The intention is clear

📌 Senior reflex:

If you see a number, give it a name.

6️⃣ Functions: Small, Single-Purpose, Clear 🎯

❌ One Function Doing Everything

function handleUser(user) {
  validateUser(user);
  saveUser(user);
  sendEmail(user);
  logUser(user);
}

Works today…
Tomorrow someone adds SMS…
Then a try/catch…
And suddenly the function collapses 😄

✅ Split and Clean Structure

function validateUser(user) {}
function saveUser(user) {}
function sendWelcomeEmail(user) {}
function logUserAction(user) {}

Why Is This Better?

• Easy to test
• Easy to debug
• Safe to change

📌 Golden Sentence:

If a function name gets long, it’s doing too much.

7️⃣ Junior vs Senior Mindset 🧠

8️⃣ Logging Culture: Even console.log Is an Art 🎨

❌ Meaningless Log

console.log(data);

✅ Meaningful Log

console.log("Order data before calculation:", data);

📌 Tip:
Logs should tell a story, not gossip 😄

🎯 CONCLUSION: Senior Code = Less Ego, More Clarity ✨

A senior developer:

• Doesn’t write acrobatic code
• Thinks: “How can I explain this more clearly?”
• Doesn’t hide errors — controls them

Remember:

Code will change one day.
Code that’s easy to change is good code. 💡