Bazel vs Closure Compiler: What are the differences?

Introduction:

Bazel and Closure Compiler are both popular tools used in web development. While Bazel is a build tool that provides local and distributed caching, robust dependency analysis, and incremental build capability, Closure Compiler is a JavaScript optimization tool that minimizes file size and improves runtime performance. Here are the key differences between Bazel and Closure Compiler:

1. Bazel is a general-purpose build tool, whereas Closure Compiler is specifically designed for JavaScript optimization: Bazel offers a comprehensive build system that can be used for various programming languages, making it suitable for large-scale software development. On the other hand, Closure Compiler focuses solely on optimizing JavaScript, providing advanced techniques for reducing file size and improving runtime performance.

2. Bazel emphasizes on sandboxed builds and remote caching, while Closure Compiler focuses on code optimization: Bazel allows for sandboxed builds, isolating build actions to ensure reproducibility and dependency management. It also offers remote caching, enabling efficient sharing of build outputs between developers. Closure Compiler, however, primarily focuses on optimizing JavaScript code, by removing dead code, renaming variables, and performing other optimizations to improve runtime performance.

3. Bazel supports various programming languages, while Closure Compiler is language-specific: Bazel supports multiple programming languages including Java, C++, Python, and more, allowing for a unified build system across different projects. Closure Compiler, on the other hand, is specifically designed for optimizing JavaScript code and does not have support for other programming languages.

4. Bazel provides an incremental build capability, while Closure Compiler optimizes entire JavaScript files: One of the key features of Bazel is its incremental build capability, which means it only builds the necessary parts of the project that have changed, reducing build times. Closure Compiler, however, optimizes entire JavaScript files, performing optimizations across the complete codebase and generating optimized code as the output.

5. Bazel enables distributed builds, while Closure Compiler focuses on local optimizations: Bazel allows for distributed builds, utilizing multiple machines to speed up the build process. This is particularly useful for large-scale projects. Closure Compiler, on the other hand, focuses on local optimizations within JavaScript files, ensuring efficient code execution at runtime.

6. Bazel integrates with various build tools and supports a wide range of build configurations, while Closure Compiler is a standalone tool: Bazel seamlessly integrates with other build tools like Maven, Gradle, and CMake, and can be customized to support different build configurations. Closure Compiler, in contrast, is a standalone tool that can be used independently for optimizing JavaScript code without extensive build configuration options.

In Summary, Bazel is a general-purpose build tool that offers sandboxed builds, remote caching, and support for multiple programming languages. Closure Compiler, on the other hand, is specifically designed for JavaScript optimization, focusing on code-level optimizations and runtime performance improvements.