JavaScript Error Handling

try...catch

Use try...catch to handle exceptions gracefully:

try {
  let result = riskyFunction();
  console.log(result);
} catch (error) {
  console.error("An error occurred:", error);
}

The code in catch only runs if an error occurs in try.

The Error Object

The caught error is usually an instance of the Error object, with helpful info:

try {
  throw new Error("Something went wrong");
} catch (e) {
  console.log(e.message);  // Something went wrong
  console.log(e.name);     // Error
}

finally Block

The finally block runs whether or not an error was thrown:

try {
  // some code
} catch (e) {
  // error handling
} finally {
  console.log("Always runs");
}

Useful for closing connections, clearing timers, etc.

Throwing Custom Errors

You can use throw to manually raise an error:

function checkAge(age) {
  if (age < 18) {
    throw new Error("User must be at least 18");
  }
  return true;
}

try {
  checkAge(15);
} catch (e) {
  alert(e.message);
}

Practical Examples

Try/catch for JSON parsing:

try {
  const user = JSON.parse('{ bad json }');
} catch (e) {
  console.log("Invalid JSON!");
}

Network or API request error catching
Form validation and exception throwing

Best Practices

Use meaningful error messages
Don’t silently suppress errors without logging
Use finally to release resources regardless of errors

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