Introduction to ES6-Error

ES6-Error is a lightweight JavaScript library that allows developers to create custom error classes more easily. By extending the built-in Error class, developers can add additional properties and methods to error objects.

Creating a Custom Error

With ES6-Error, creating custom errors is straightforward. Here is an example:

  
    const ExtendableError = require('es6-error');

    class MyCustomError extends ExtendableError {
      constructor(message) {
        super(message);
        this.name = 'MyCustomError';
      }
    }

    throw new MyCustomError('Something went wrong!');
  

Adding Properties to Custom Errors

You can add custom properties to your custom error classes.

  
    class ValidationError extends ExtendableError {
      constructor(message, field) {
        super(message);
        this.name = 'ValidationError';
        this.field = field;
      }
    }

    const error = new ValidationError('Invalid input', 'username');
    console.log(error.field); // 'username'
  

Using Custom Methods in Errors

Custom methods can be added to enhance error objects.

  
    class NetworkError extends ExtendableError {
      constructor(message, code) {
        super(message);
        this.name = 'NetworkError';
        this.code = code;
      }

      getCode() {
        return this.code;
      }
    }

    const error = new NetworkError('Network is down', 503);
    console.log(error.getCode()); // 503
  

Real-world Application Example

Using custom errors in a node application to handle specific issues gracefully:

  
    const express = require('express');
    const ExtendableError = require('es6-error');

    class ApiError extends ExtendableError {
      constructor(message, statusCode) {
        super(message);
        this.name = 'ApiError';
        this.statusCode = statusCode;
      }
    }

    class NotFoundError extends ApiError {
      constructor(message) {
        super(message, 404);
        this.name = 'NotFoundError';
      }
    }

    class ValidationError extends ApiError {
      constructor(message) {
        super(message, 400);
        this.name = 'ValidationError';
      }
    }

    const app = express();

    app.get('/data', (req, res, next) => {
      try {
        const data = getData();
        if (!data) {
          throw new NotFoundError('Data not found');
        }
        res.send(data);
      } catch (error) {
        next(error);
      }
    });

    app.use((err, req, res, next) => {
      if (err instanceof ApiError) {
        res.status(err.statusCode).send({ error: err.message });
      } else {
        res.status(500).send({ error: 'Internal Server Error' });
      }
    });

    app.listen(3000, () => {
      console.log('Server started on http://localhost:3000');
    });
  

In this example, we create a custom ApiError class along with specific NotFoundError and ValidationError classes. These custom errors allow us to handle different types of errors more effectively within an Express application.

By leveraging the power of ES6-Error, you can create more robust and maintainable error handling in your JavaScript applications.

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