Exception Handling (try/catch)

Jab kuch ghalat ho jaata hai — invalid JSON parse karna, aisa method call karna jo mojood hi nahi hota — JavaScript ek error throw karta hai. Agar pakra na jaaye to yeh aapka program crash kar deta hai. try/catch aapko use pakarne aur decide karne deta hai ke 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 chalane ki koshish karta hai. Jaise hi JSON.parse() throw karta hai, yeh seedha catch block mein chala jaata hai crash hone ke bajaye — uske baad program normal tor par chalta rehta hai.

Asal error ko access karna, aur finally

catch (error) aapko asal error object tak rasaai deta hai — logging ke liye ya generic ke bajaye ek real message dikhane ke liye kaam aata hai. finally hamesha chalta hai chahe kuch bhi hua ho — error throw hui 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 asal JavaScript engine se aaya hai, kuch aisa nahi jo plausible dikhne ke liye likha gaya ho — yeh waqai woh hai jo aap yeh exact code chala kar dekhoge.

Aage: classes — data aur uspar kaam karne wale functions ko sath mein jorna.