let’s start with reality.

👉 errors avoid nahi hote 👉 errors handle kiye jaate hain

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Sabse Pehle — Error Kya Hota Hai?

simple line:

👉 jab code expected tarike se run nahi karta → error

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Ek Basic Example

console.log(name);

output:

ReferenceError: name is not defined

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Types of Errors (Short Mein)

• ReferenceError → variable exist nahi karta

• TypeError → galat type pe kaam kar rahe ho

• SyntaxError → code likhne mein mistake

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Real Problem ⚠️

agar error aaya…

👉 pura program crash ho sakta hai 👉 baaki code run hi nahi karega

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Example

console.log("Start");

console.log(name); // error

console.log("End");

output:

Start
(error)

👉 "End" kabhi run nahi hua

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Yahan Entry Hoti Hai — try/catch 🚀

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try aur catch — Basic Idea

👉 try = risky code likho 👉 catch = agar error aaye toh handle karo

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Example

try {
  console.log(name);
} catch (error) {
  console.log("Error aa gaya bhai 😅");
}

---

Output

Error aa gaya bhai 😅

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Important Point

👉 program crash nahi hua 👉 gracefully handle ho gaya

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Real Life Example

socho tum ATM pe ho 💳

• try → paise nikaalne ki koshish

• catch → "insufficient balance" message

ATM blast nahi karta 😄 woh error handle karta hai.

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try/catch Flow Samjho

try block run karo
↓
agar error aaya → catch run
↓
agar error nahi aaya → catch skip

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finally Block — Hidden Hero ⭐

finally ka simple matlab:

👉 "yeh toh har condition mein chalega"

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Example

try {
  console.log("Try chal raha hai");
} catch (err) {
  console.log("Error handle hua");
} finally {
  console.log("Finally hamesha chalega");
}

---

Output

Try chal raha hai
Finally hamesha chalega

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Agar Error Aaye Toh?

try {
  console.log(name);
} catch (err) {
  console.log("Error handle hua");
} finally {
  console.log("Finally chalega");
}

---

Output

Error handle hua
Finally chalega

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Use Case

👉 cleanup kaam 👉 closing resources 👉 logging

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Throwing Custom Errors

kabhi kabhi tum khud error create karna chahte ho.

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Example

const age = 15;

if (age < 18) {
  throw new Error("Not allowed 😡");
}

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Result

👉 error manually throw hua

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try/catch ke saath

try {
  const age = 15;

  if (age < 18) {
    throw new Error("Underage user");
  }

} catch (err) {
  console.log(err.message);
}

---

Output

Underage user

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Real Life Example

login system 🔐

👉 password wrong → custom error 👉 email missing → custom error

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Why Error Handling Matters

1. App crash se bachata hai

without handling:

👉 app band

with handling:

👉 app chalta rehta hai

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2. Better User Experience

instead of:

❌ "Something went wrong"

you can show:

✅ "Server busy hai, thodi der baad try karo"

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3. Debugging Easy

catch (err) {
  console.log(err);
}

👉 error trace milta hai

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4. Production Ready Code

real apps mein:

👉 har API fail ho sakti hai 👉 network slow ho sakta hai

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Async Error Handling ⚠️

important part.

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Wrong Way ❌

try {
  fetch("https://api.com");
} catch (err) {
  console.log(err);
}

👉 yeh kaam nahi karega

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Correct Way ✅

async function getData() {
  try {
    const res = await fetch("https://api.com");
    const data = await res.json();
    console.log(data);
  } catch (err) {
    console.log("Error:", err);
  }
}

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Insight

👉 async code ke liye await + try/catch use karo

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One Powerful Line

👉 errors avoid nahi hote — unhe handle karna padta hai

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Flow of try and catch

        try
         ↓
   (error?)
    /     \
 yes       no
 ↓         ↓
catch     skip
   ↓
finally (always runs)

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Real Example — API + Error Handling

async function loadUser() {
  try {
    console.log("Loading...");

    const res = await fetch("https://wrong-url.com");

    if (!res.ok) {
      throw new Error("API failed");
    }

    const data = await res.json();

    console.log(data);

  } catch (err) {
    console.log("Something went wrong:", err.message);
  } finally {
    console.log("Request finished");
  }
}

---

Output

Loading...
Error message
Request finished

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Common Mistakes ❌

1. Empty catch

catch (err) {}

👉 debugging nightmare

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2. Overusing try/catch

👉 har line pe mat lagao 👉 sirf risky code pe use karo

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3. Ignoring error message

console.log("Error");

👉 useless

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Best Practice

👉 meaningful messages 👉 logging 👉 user-friendly response

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Assignment (Try Karo)

1. ek error intentionally create karo

2. try/catch se handle karo

3. custom error throw karo

4. async API call pe error handle karo

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Final Thought

good developer woh nahi jo kabhi error nahi karta.

good developer woh hai jo:

👉 error ko control mein rakhta hai

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One Line Summary

👉 try = risky code 👉 catch = error handle 👉 finally = always run

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Connect with me here :

Twitter or X : https://x.com/Curious_Karann
LinkedIn : https://www.linkedin.com/in/karan-hingrajiya-82a78b2a4/

See you in the next blog !! until then keep growing and keep coding 🔥!!