If you haven’t heard of WebAssembly yet, then you will soon. It’s one of the industry’s best-kept secrets, but it’s everywhere. It’s supported by all the major browsers, and it’s coming to the server-side, too. It’s fast. It’s being used for gaming. It’s an open standard from the World Wide Web Consortium (W3C), the main international standards organization for the web. Where did it come from? Going back about ten years, there was a growing recognition that the widely-used JavaScript wasn’t fast enough for many purposes. JavaScript was undoubtedly successful and convenient. It ran in any browser and enabled the type of dynamic web pages that we take for granted today. But it was a high-level language and wasn’t designed with compute-intensive workloads in mind. However, although engineers responsible for the leading web browsers were generally in agreement about the performance problem, they weren’t aligned on what to do about it. Two camps emerged. Google began its Native Client project and, later, its Portable Native Client variation, to focus on allowing games and other software written in C/C++ to run in a secure compartment within Chrome. Mozilla, meanwhile, won the backing of Microsoft for asm.js, an approach that updated the browser so it can run a low-level subset of JavaScript instructions very quickly (another project enabled the conversion of C/C++ code into these instructions). With neither camp gaining widespread adoption, the various parties agreed to join forces in 2015 around a new standard called WebAssembly that built on the basic approach taken by asm.js. As CNET’s Stephen Shankland wrote at the time, On today’s Web, the browser’s JavaScript translates those instructions into machine code. But with WebAssembly, the programmer does a lot of the work earlier in the process, producing a program that’s in between the two states. That frees the browser from a lot of the hard work of creating the machine code, but it also fulfills the promise of the Web—that software will run on any device with a browser regardless of the underlying hardware details.
