At this point in time deploying Rust and WebAssembly to the web or other locations unfortunately isn‘t a trivial task to do. This page hopes to serve as documentation for the various known options, and as always PRs are welcome to update this if it’s out of date!
The methods of deployment and integration here are primarily tied to the --target
flag. Note that the --target
flag of wasm-pack
and wasm-bindgen
should behave the same way in this respect. The values possible here are:
Value | Summary |
---|---|
bundler | Suitable for loading in bundlers like Webpack |
web | Directly loadable in a web browser |
nodejs | Loadable via require as a Node.js module |
no-modules | Like web , but older and doesn't use ES modules |
--target bundler
The default output of wasm-bindgen
, or the bundler
target, assumes a model where the wasm module itself is natively an ES module. This model, however, is not natively implemented in any JS implementation at this time. As a result, to consume the default output of wasm-bindgen
you will need a bundler of some form.
Note: the choice of this default output was done to reflect the trends of the JS ecosystem. While tools other than bundlers don‘t support wasm files as native ES modules today they’re all very much likely to in the future!
Currently the only known bundler known to be fully compatible with wasm-bindgen
is webpack. Most examples use webpack, and you can check out the hello world example online to see the details of webpack configuration necessary.
--target web
or --target no-modules
If you‘re not using a bundler but you’re still running code in a web browser, wasm-bindgen
still supports this! For this use case you'll want to use the --target web
flag. You can check out a full example in the documentation, but the highlights of this output are:
--target web
to wasm-pack
(or wasm-bindgen
directly).--target web
mode is not able to use NPM dependencies.wasm-bindgen
because no polyfills will be available.The CLI also supports an output mode called --target no-modules
which is similar to the web
target in that it requires manual initialization of the wasm and is intended to be included in web pages without any further postprocessing. See the without a bundler example for some more information about --target no-modules
.
--target nodejs
If you‘re deploying WebAssembly into Node.js (perhaps as an alternative to a native module), then you’ll want to pass the --target nodejs
flag to wasm-pack
or wasm-bindgen
.
Like the “without a bundler” strategy, this method of deployment does not require any further postprocessing. The generated JS shims can be require
'd just like any other Node module (even the *_bg
wasm file can be require
'd as it has a JS shim generated as well).
Note that this method requires a version of Node.js with WebAssembly support, which is currently Node 8 and above.
If you'd like to deploy compiled WebAssembly to NPM, then the tool for the job is wasm-pack
. More information on this coming soon!