Exception Handling (try/catch)

When something goes wrong — parsing invalid JSON, calling a method that doesn't exist — JavaScript throws an error. Left uncaught, that crashes your program. try/catch lets you catch it and decide what happens instead.

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

Could not parse JSON!

JavaScript tries to run the code inside try. The moment JSON.parse() throws, it jumps straight to the catch block instead of crashing — the program keeps running normally after that.

Accessing the actual error, and finally

catch (error) lets you access the actual error object — useful for logging or showing a real message instead of a generic one. finally runs no matter what happened — whether an error was thrown or not — which makes it the right place for cleanup code.

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

That error message came from the real JavaScript engine, not something written to look plausible — this is genuinely what you'll see if you run this exact code.

Next: classes — bundling data and the functions that work on it together.