Sequelize vs TypeORM: What are the differences?

Both Sequelize and TypeORM are popular Object-Relational Mapping (ORM) libraries in the Node.js ecosystem. They allow developers to interact with relational databases using JavaScript/TypeScript, abstracting away the underlying SQL.

Here are some differences between the two that might help you make a decision:

1. Language support: Sequelize is written in JavaScript and supports JavaScript and TypeScript, while TypeORM is written in TypeScript and supports TypeScript.

2. Query building: Sequelize and TypeORM use distinct approaches to interact with databases. Sequelize follows the query builder approach, which involves chaining methods to form queries. On the other hand, TypeORM uses the data mapper approach, where you work with entities and use methods such as find or save to interact with the database.

3. Relationships: TypeORM has better support for complex relationships, such as many-to-many relationships, while Sequelize requires more manual configuration to set up such relationships.

4. Active development: TypeORM is a newer library and has a more active development community than Sequelize.

5. Database support: Sequelize is compatible with a variety of databases such as MySQL, PostgreSQL, SQLite, and MSSQL. On the other hand, TypeORM has the capability to work with MySQL, PostgreSQL, SQLite, Oracle, SQL Server, CockroachDB, and MongoDB.

Overall, if you prefer a data mapper approach and want better support for complex relationships, TypeORM might be a better fit for your project. If you prefer a query builder approach and need to support a wider range of databases, Sequelize might be a better fit.