| # Converting WebAssembly to JS |
| |
| [View full source code][code] |
| |
| [code]: https://github.com/rustwasm/wasm-bindgen/tree/master/examples/wasm2js |
| |
| Not all browsers have support for `WebAssembly` at this time (although all major |
| ones do). If you'd like to support older browsers, you probably want a method |
| that doesn't involve keeping two codebases in sync! |
| |
| Thankfully there's a tool from [binaryen] called `wasm2js` to convert a wasm |
| file to JS. This JS file, if successfully produced, is equivalent to the wasm |
| file (albeit a little bit larger and slower), and can be loaded into practically |
| any browser. |
| |
| This example is relatively simple (cribbing from the [`console.log` |
| example](console-log.md)): |
| |
| ```rust |
| {{#include ../../../examples/wasm2js/src/lib.rs}} |
| ``` |
| |
| The real magic happens when you actually build the app. Just after |
| `wasm-bindgen` we see here how we execute `wasm2js` in our build script: |
| |
| ```sh |
| {{#include ../../../examples/wasm2js/build.sh}} |
| ``` |
| |
| Note that the `wasm2js` tool is still pretty early days so there's likely to be |
| a number of bugs to run into or work around. If any are encountered though |
| please feel free to report them upstream! |
| |
| Also note that eventually this will ideally be automatically done by your |
| bundler and no action would be needed from you to work in older browsers via |
| `wasm2js`! |
| |
| [binaryen]: https://github.com/WebAssembly/binaryen |
