JS calls brought in for every compile for WASM

[ranile]

When compiling for wasm, the only option is to bring in JS bindings for web APIs. However, wasm is used a for a lot more than just browsers or runtime with web APIs available, causing this library to be unusable in those cases.

One such example is https://forum.dfinity.org/t/module-imports-function-wbg-now-2e07eedfb4ac9dbe-from-wbindgen-placeholder-that-is-not-exported-by-the-runtime/22083, with me also running into the same issue.

Culprit code

https://github.com/Keats/jsonwebtoken/blob/5cd1887848f7d30f11adb4ebcec6a01baffd5252/Cargo.toml#L30-L35

Solution

Give option to opt out of JS calls on wasm targets. One way to do that is to move JS calls behind a feature flag, similar to the ring crate that is enabled here. Note that wasm32-unknown-unknown target is not enough to assume that JS API will be available, as is the case for the platform of the forum post linked above