Cargo Features

[dependencies]
wasm-bindgen-spawn = { version = "0.0.1", default-features = false, features = ["async"] }
default = async

The async feature is set by default whenever wasm-bindgen-spawn is added without default-features = false somewhere in the dependency tree.

async default = wasm-bindgen-futures

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features. These features may have been created by mistake, and this functionality may be removed in the future.

wasm-bindgen-futures async