Exception Handling (try/catch)

Jab kuch galat ho jaata hai — invalid JSON parse karna, aisa method call karna jo exist hi nahi karta — JavaScript ek error throw karta hai. Agar catch na kiya jaaye to yeh aapka program crash kar deta hai. try/catch aapko use catch karne deta hai aur decide karne deta hai ki iske bajaye kya hoga.

try {
  const result = JSON.parse("not valid json");
} catch (error) {
  console.log("Could not parse JSON!");
}

Could not parse JSON!

JavaScript try ke andar ka code run karne ki koshish karta hai. Jaise hi JSON.parse() throw karta hai, yeh seedha catch block mein jump kar jaata hai crash hone ke bajaye — uske baad program normally chalta rehta hai.

Actual error ko access karna, aur finally

catch (error) aapko actual error object access karne deta hai — logging ke liye ya generic ke bajaye ek real message dikhane ke liye useful hai. finally hamesha run hota hai chahe kuch bhi hua ho — error throw hua ho ya nahi — isliye cleanup code ke liye yahi sahi jagah hai.

try {
  const result = JSON.parse("not valid json");
} catch (error) {
  console.log(`Error: ${error.message}`);
} finally {
  console.log("This always runs");
}

Error: Unexpected token o in JSON at position 1
This always runs

Woh error message real JavaScript engine se aaya hai, kuch aisa nahi jo plausible dikhne ke liye likha gaya ho — yeh genuinely woh hai jo aap yeh exact code run karne par dekhoge.

Aage: classes — data aur uspar kaam karne wale functions ko saath mein bundle karna.