Error Types and Custom Errors

JavaScript provides several built-in error constructors, such as Error, SyntaxError, ReferenceError, and TypeError. Understanding these helps you debug issues faster.

Built-in Errors

When code violates the rules of the language, the engine throws standard errors:

• ReferenceError: Raised when you use a variable that doesn't exist.
• TypeError: Raised when a value is not of the expected type.

Throwing Errors

You can manually throw errors using the throw keyword. It's best practice to throw an Error object (or a subclass) rather than a string, as objects capture the stack trace.

Custom Error Classes

For complex applications, generic errors aren't enough. You can extend the built-in Error class to create specific error types. This allows callers to catch specific errors using instanceof.