How can I create a custom error class in JavaScript and handle it with try/catch to provide detailed error messages?

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How can I create a custom error class in JavaScript and handle it with try/catch to provide detailed error messages?

Asked on Dec 24, 2025

Answer

To create a custom error class in JavaScript, extend the built-in Error class. This allows you to throw and catch custom errors with detailed messages.

<!-- BEGIN COPY / PASTE -->
        class CustomError extends Error {
            constructor(message) {
                super(message);
                this.name = "CustomError";
            }
        }

        try {
            throw new CustomError("This is a custom error message.");
        } catch (error) {
            if (error instanceof CustomError) {
                console.error(`Custom error caught: ${error.message}`);
            } else {
                console.error(`General error caught: ${error.message}`);
            }
        }
        <!-- END COPY / PASTE -->

Additional Comment:

This example defines a "CustomError" class that extends the "Error" class.
The "try" block throws a "CustomError" with a specific message.
The "catch" block checks if the error is an instance of "CustomError" and logs a custom message.
If the error is not a "CustomError", it logs a general error message.

✅ Answered with JavaScript best practices.

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How can I create a custom error class in JavaScript and handle it with try/catch to provide detailed error messages?

Asked on Dec 24, 2025

Answer

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