**Course Title:** Build and Package Management in Modern Development **Section Title:** Managing Dependencies with NPM/Yarn **Topic:** Semantic Versioning: Understanding Version Numbers **Introduction** In the world of software development, managing dependencies is crucial for maintaining a stable and efficient project. One key aspect of dependency management is understanding version numbers. Semantic Versioning (semver) is a widely adopted standard for versioning packages in a way that's easy to understand and communicate. In this topic, we'll dive into the world of Semantic Versioning and explore its ins and outs. **What is Semantic Versioning?** Semantic Versioning (semver) is a versioning system that assigns a unique version number to each release of a package. This version number is composed of three digits: Major, Minor, and Patch. The semver system provides a clear and predictable way to manage version numbers, making it easier for developers to understand and manage dependencies. **Understanding Version Numbers** A semver version number typically follows this format: `major.minor.patch` Let's break it down: * **Major (X)**: The major version represents significant changes, breaking backward compatibility, or introducing major features. Incrementing the major version indicates a major shift in the package's functionality. * **Minor (Y)**: The minor version represents new functionality, API additions, or bug fixes that don't break backward compatibility. Incrementing the minor version indicates a minor change to the package's functionality. * **Patch (Z)**: The patch version represents bug fixes, security patches, or minor adjustments that don't introduce new functionality. Incrementing the patch version indicates a bug fix or minor adjustment. **Versioning Rules** Here are some key rules to keep in mind when using semver: * **Incrementing the major version** (e.g., from 1.2.3 to 2.0.0) should only occur when there are breaking backward compatibility changes or significant changes to the package's functionality. * **Incrementing the minor version** (e.g., from 1.2.3 to 1.3.0) should only occur when new functionality is added that doesn't break backward compatibility. * **Incrementing the patch version** (e.g., from 1.2.3 to 1.2.4) should only occur when bug fixes or minor adjustments are made. **Semantic Versioning Example** Let's say we're working on a package called `my-package`. We've just added a new feature that introduces a breaking change. We should increment the major version: `v1.2.3` → `v2.0.0` Next, we've fixed a bug and added some minor improvements. We can increment the patch version: `v2.0.0` → `v2.0.1` Later, we've added a new feature that doesn't break backward compatibility. We can increment the minor version: `v2.0.1` → `v2.1.0` **Using Semver with NPM and Yarn** Both NPM and Yarn support semver versioning. When specifying a package version in your `package.json` file, you can use semver syntax to specify the version range. For example: ```json "dependencies": { "express": "^4.17.1" } ``` The `^` symbol indicates that the package version can be updated to any version up to the next major version. You can also use the `~` symbol to allow updates to the next patch version: ```json "dependencies": { "express": "~4.17.1" } ``` **Best Practices** * Use semver versioning consistently across your projects and packages. * Increment version numbers carefully, taking into account the rules outlined above. * Use `package.json` version ranges to control dependencies and ensure compatibility. **Conclusion** Semantic Versioning is a powerful tool for managing package versions and ensuring compatibility across projects. By following the rules and best practices outlined in this topic, you'll be able to manage your package versions effectively and communicate changes to your dependencies clearly. Remember, mastering semantic versioning takes time and practice. Be patient, and you'll become a versioning expert! **Additional Resources** * [Semantic Versioning (semver.org)](https://semver.org/) * [NPM Semver Documentation](https://docs.npmjs.com/cli/v7/using-npm/semver) * [Yarn Semver Documentation](https://classic.yarnpkg.com/en/docs/cli/semver) **What's Next?** In our next topic, we'll dive into lock files (npm-shrinkwrap.json and yarn.lock). These files help ensure dependency versions remain consistent across development environments. Stay tuned! **Do you have any questions or need further clarification on semantic versioning?**