Cargo Features

[dependencies]
elm-rust-binding = { version = "0.4.0", default-features = false, features = ["v8", "quickjs"] }
default = v8

The v8 feature is set by default whenever elm-rust-binding is added without default-features = false somewhere in the dependency tree.

v8 default = rustyscript
quickjs = quickjs_runtime

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.

quickjs_runtime quickjs?
rustyscript v8