express-validator vs joi: What are the differences?

Introduction

This Markdown code provides a comparison between express-validator and joi, two popular validation libraries used in web development.

1. Built-in Validator Functions: express-validator offers a comprehensive set of built-in validator functions, such as isEmail, isInt, isLength, isURL, and more. These functions allow developers to easily validate specific properties of user inputs. Conversely, joi does not provide built-in validator functions, requiring developers to define custom validation rules or use external plugins.

2. Middleware Support: express-validator is designed as a middleware for Express.js, allowing developers to seamlessly integrate it into their Express applications. On the other hand, joi is a standalone validation library that can be used with any Node.js framework, but requires additional implementation to be used specifically with Express.js.

3. Sanitization: express-validator includes sanitization functions alongside validation functions. These functions allow developers to sanitize user inputs by removing or sanitizing potentially harmful content. joi, on the other hand, focuses solely on validation and does not provide built-in sanitization functions.

4. Promise-Based Validation: joi supports promise-based validation, allowing developers to chain multiple validations together using promises. This feature enables developers to easily perform complex validation logic in a readable and concise manner. express-validator does not provide built-in support for promise-based validation, requiring developers to handle asynchronous operations themselves.

5. Custom Error Messages: express-validator allows developers to customize error messages for each validation rule, making it easier to provide meaningful feedback to users. joi also supports custom error messages, but requires additional configuration and syntax to define these messages.

6. Plugin Ecosystem: express-validator has a large and active plugin ecosystem, providing additional validation and sanitization functions. This allows developers to easily extend the functionality of express-validator based on their specific requirements. In comparison, joi has a more limited plugin ecosystem, potentially requiring developers to implement custom validation logic from scratch.

In summary, express-validator provides a more extensive set of built-in validator and sanitization functions, integrates seamlessly with Express.js as middleware, supports custom error messages, but lacks built-in promise-based validation and has a more robust plugin ecosystem. On the other hand, joi is a standalone validation library, supports promise-based validation and allows for more customizable error messages, but lacks built-in sanitization functions and has a more limited plugin ecosystem.