Node is built on standard open source C libraries. For example, the TLS and SSL protocols are implemented by OpenSSL. More than just adopting an API, the C source code of OpenSSL is included and complied into Node. When your JavaScript program hashes a cryptographic key, it's not JavaScript that's actually doing the work. Your JavaScript, run by Node, has called down to the C code of OpenSSL. Essentially, you are scripting the native library.
This design choice of using the existing and proven open source libraries helped Node in a number of ways:
- It meant that Node could arrive on the scene very rapidly, with the core set of functionality systems programmers needed and expected already there
- It ensures performance, reliability, and security continues to match the libraries
- It also didn't break cross-platform use, as all of these C libraries have been written and maintained to compile for different architectures for years
Previous platforms and languages have made a different choice in trying to achieve software portability. The 100% Pure Java™ Standard, for instance, was a Sun Microsystems initiative to promote the development of portable applications. Rather than leveraging the existing code in a hybrid stack, it encouraged developers to rewrite everything in Java. Developers had to keep features, performance, and security up to the standard by writing and testing new code. Node, on the other hand, picked a design that gets this all for free.
