Error Handling in Javascript: Try, Catch, Finally

So, what do you mean by Errors in JavaScript?

Well technically!!!...

Errors are issues that occur when your JavaScript code stops executing as expected.

But wait…

This sounds like your maths teacher explaining integration 😵‍💫

So let’s understand this in our way.

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When Life Breaks… JavaScript Also Breaks

Imagine this:

You are ordering food online 🍔

You click “Place Order”…

And suddenly… nothing happens.

No confirmation, no error, no refund

Just silence…

That… my friend… is what we call bad error handling.

Now let’s bring this to code.

console.log(user.name);

But…

const user = null;

Boom 💥

👉 Error: Cannot read properties of null

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Types of Errors (Real Life Style)

JavaScript errors are mainly of 3 types:

1. Syntax Error

Your code is written incorrectly.

Like writing:

if (true {
  console.log("Hello");
}

Missing )… and JavaScript says:

👉 “Bhai pehle grammar seekh ke aa”

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2. Runtime Error

Code runs… but crashes during execution.

const user = null;
console.log(user.name);

This is like:

You reached the restaurant… but it's closed 🚪

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3. Logical Error

Code runs perfectly… but gives wrong result.

const total = 10 + "5"; // "105"

This is like:

You ordered pizza… got pineapple pizza 🍍🍕

Technically correct… emotionally wrong.

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Now Comes the Hero — try & catch

So how do we handle errors?

JavaScript gives us a bodyguard 🛡️

👉 try...catch

try {
  const user = null;
  console.log(user.name);
} catch (error) {
  console.log("Something went wrong");
}

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How it works?

• try → Run risky code

• catch → Handle error if it occurs

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Real Life Example

You are transferring money 💸

try {
  transferMoney();
} catch (error) {
  console.log("Transaction failed. Please try again.");
}

Instead of app crashing…

👉 User sees a message 👉 Business saves reputation 👉 You save your job 😅

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The Flow (Important)

Try to visualize this:

Start
  ↓
try block runs
  ↓
Error?
  ↓         ↓
No          Yes
↓           ↓
skip catch  catch runs
  ↓
finally runs (always)
  ↓
End

Yes… there is one more player 👇

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The Finally Block (The Honest Worker)

No matter what happens…

finally will always run.

try {
  console.log("Trying...");
} catch (error) {
  console.log("Error occurred");
} finally {
  console.log("I will always run 😎");
}

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Real Life Example

ATM Machine:

try {
  withdrawMoney();
} catch (error) {
  console.log("Transaction failed");
} finally {
  ejectCard(); // always happens
}

Even if money fails…

👉 Card always comes out

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Throwing Custom Errors (Ab Developer Bolega 😎)

Sometimes default errors are not enough.

We want to control the message.

function withdraw(amount) {
  if (amount > 10000) {
    throw new Error("Limit exceeded bhai 😅");
  }
  return "Money withdrawn";
}

try {
  withdraw(20000);
} catch (error) {
  console.log(error.message);
}

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Why This is Powerful?

Instead of random crash…

👉 You define the problem 👉 You define the message 👉 You guide the user

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Graceful Failure (The Real Goal)

Good developers don’t write bug-free code…

👉 They write code that fails gracefully

Bad Example ❌ App crashes

Good Example ✅ App says:

“Something went wrong, please try again”

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Debugging Benefits (Why You Should Care)

Error handling helps you:

• Find bugs faster 🔍

• Prevent app crashes 🚫

• Improve user experience ❤️

• Write production-ready code 🚀

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One Small Example (Real World Combo)

function login(user) {
  try {
    if (!user) {
      throw new Error("User not found");
    }

    console.log("Welcome " + user.name);

  } catch (error) {
    console.log(error.message);
  } finally {
    console.log("Login attempt finished");
  }
}

login(null);

Output:

User not found
Login attempt finished

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Final Thoughts

Errors are not enemies…

They are signals 🚨

They tell you:

👉 “Something is wrong… fix me”

If you ignore them…

Your app becomes chaos 😵

If you handle them…

You become a real developer 💪

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Homework (Don’t Run Away 😏)

Q1

What will be the output?

try {
  console.log(a);
} catch (e) {
  console.log("Error handled");
}

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Q2

Fix this code using try-catch:

const data = JSON.parse("{name: 'Barun'}");
console.log(data);

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Q3

Create a function:

• If age < 18 → throw error

• Else → print "Access granted."

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Last Line (Important)

A good developer writes code…

A great developer handles failure.

And trust me…

In real world…

Failure comes more often than success 😄

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Inspired by the style and storytelling approach from the shared blog examples