Agunechemba Ekene

When coding in JavaScript, sometimes errors happen—maybe a user inputs wrong data, or a file doesn’t load. Instead of letting your whole program crash, JavaScript gives you a way to handle errors smoothly using try...catch.

What Are try and catch?

  • try: This block contains the code you want JavaScript to try running. If everything goes well, it runs normally.

  • catch: This block runs only if an error occurs in the try block. It “catches” the error so you can handle it (like showing a message or fixing the issue) instead of the program crashing.

Example Code

try {
  let number = 10;
  if (number > 5) {
    throw "Number is too big!";
  }
  console.log("This won't run.");
} catch (error) {
  console.log("Caught an error: " + error);
}

What’s Happening Here?

  1. The code inside the try block runs first.

  2. We check if number is greater than 5. Since 10 is greater than 5, the code throws an error with the message "Number is too big!".

  3. When the error is thrown, the program stops running the rest of the try block. So, console.log("This won't run.") is skipped.

  4. The error is passed to the catch block, which catches it and prints:

    Caught an error: Number is too big!

Why Use try...catch?

Because it helps keep your program running even when unexpected things happen. Instead of crashing, you get a chance to handle the error gracefully.

Quick Recap:

  • Use try to run risky code.
  • Use catch to handle errors when they happen.
  • Use throw if you want to create a custom error inside try.

Review Questions

1. What does the try block do in JavaScript? A) Handles errors after they occur B) Contains code that JavaScript attempts to run C) Stops the program if an error happens D) Creates custom error messages

2. When does the catch block run? A) Always after the try block finishes B) Only if an error occurs inside the try block C) Before the try block runs D) When the program finishes successfully

3. What happens when a throw statement is executed inside a try block? A) The program continues as normal B) The error is ignored C) The rest of the try block is skipped, and control moves to catch D) The try block runs again

4. Why is try...catch useful in JavaScript programming? A) To create infinite loops B) To keep the program running even when errors occur C) To slow down the code execution D) To prevent any code from running

5. Which statement is true about catch? A) It only runs if no errors occur B) It is used to define a variable C) It catches and handles errors thrown in the try block D) It throws errors

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