How does 'throw new Error' differ from 'throw customObject'?

I’m developing a universal error handler to catch user-defined errors throughout the code.

Using ‘throw new Error’ like this:

try {
    throw new Error({foo: 'bar'});
} catch(e) {
    console.log(e);
}

In the Firefox console, it logs as ‘Error: [object Object]’, which is not easily parsed. For ‘throw new Error(“foo”)’, the log is ‘Error: foo’.

Alternatively:

try {
    throw {foo: 'bar'};
} catch(e) {
    console.log(e);
}

shows ‘Object { foo: “bar” }’, enabling access to the object’s properties.

What’s fundamentally different here? Is it that strings remain strings while objects keep their structure, with different syntax? I’ve mainly worked with string errors—any alternatives to these methods?

Hey there! When dealing with error handling in JavaScript, using throw new Error() wraps your provided message or object inside an actual Error object. This structure indeed simplifies string messaging but loses object detail. For better object handling, directly throwing an object like {foo: 'bar'} retains its structure, allowing you to access its properties conveniently. :art:

If you mainly need to preserve the object structure, stick to throwing plain objects or consider creating a custom error class for a more formal approach!

In JavaScript, handling errors efficiently can really make debugging easier and your code cleaner. If your intention is to throw and catch errors with structured data, you have a couple of options to consider beyond the traditional throw new Error() approach.

Here’s a straightforward explanation and an alternative solution:

Understanding the Difference:

When you use throw new Error('foo'), JavaScript wraps your message in an Error object, which primarily holds a string. This is great for simple string error messages but not ideal for error details stored in objects.

If you directly throw an object like {foo: 'bar'}, you maintain the object structure and can easily manipulate its properties when caught. This approach provides more flexibility if you need to access complex data associated with an error.

Custom Error Class Approach:

For those looking for a structured solution while retaining an official error handling approach, consider creating a custom error class. This provides a way to throw well-defined errors that contain additional data:

class CustomError extends Error {
  constructor(message, data) {
    super(message);
    this.data = data; // Add extra properties
  }
}

try {
  throw new CustomError('An error occurred', { foo: 'bar' });
} catch (e) {
  console.log(e.message); // 'An error occurred'
  console.log(e.data);    // { foo: 'bar' }
}

Quick Tips:

  • Use Error class when you need simple string messages.
  • Use plain objects for easy-to-access, structured data.
  • Use custom error classes for a formal approach with detailed information.

By choosing the appropriate method, you can make your error handling robust, ensuring that you’re well-prepared to troubleshoot issues effectively.

Hey! It looks like you’re diving into error handling in JavaScript, which can be quite fun! :smile: When you “throw new Error()”, you’re wrapping your message inside an Error object, best for simple text messages. However, if you want to keep the structure of an object, throwing a plain object will do the trick, like this:

try {
    throw { foo: 'bar' };
} catch (e) {
    console.log(e); // Logs: { foo: 'bar' }
}

This way, you can access the properties easily when you catch the error. If you want a bit more formality and flexibility, try creating a custom error class. Here’s a quick example:

class CustomError extends Error {
  constructor(message, data) {
    super(message);
    this.data = data; // You can add more properties here
  }
}

try {
  throw new CustomError('Oops!', { foo: 'bar' });
} catch (e) {
  console.log(e.message); // Logs: 'Oops!'
  console.log(e.data);    // Logs: { foo: 'bar' }
}

This setup lets you have the best of both worlds: structured data with a recognizable error format. Just choose what fits your needs better! If you need any more tips, feel free to ask. :blush: