Contents

# `Result<T, E>`

| `T` parameter | `&T` parameter | `&mut T` parameter | `T` return value | `Option<T>` parameter | `Option<T>` return value | JavaScript representation |
|:---:|:---:|:---:|:---:|:---:|:---:|:---:|
| No | No | No | Yes | No | No | Same as `T`, or an exception |

The `Result` type can be returned from functions exported to JS as well as
closures in Rust. The `Ok` type must be able to be converted to JS, and the
`Err` type must implement `Into<JsValue>`. Whenever `Ok(val)` is encountered
it's converted to JS and handed off, and whenever `Err(error)` is encountered
an exception is thrown in JS with `error`.

You can use `Result` to enable handling of JS exceptions with `?` in Rust,
naturally propagating it upwards to the wasm boundary. Furthermore you can also
return custom types in Rust so long as they're all convertible to `JsValue`.

Note that if you import a JS function with `Result` you need
`#[wasm_bindgen(catch)]` to be annotated on the import (unlike exported
functions, which require no extra annotation). This may not be necessary in the
future though and it may work "as is"!.

Version data entries

30 entries across 30 versions & 1 rubygems

Version	Path
wasmtime-23.0.2	./ext/cargo-vendor/wasm-bindgen-0.2.89/guide/src/reference/types/result.md
wasmtime-22.0.0	./ext/cargo-vendor/wasm-bindgen-0.2.89/guide/src/reference/types/result.md
wasmtime-21.0.1	./ext/cargo-vendor/wasm-bindgen-0.2.89/guide/src/reference/types/result.md
wasmtime-20.0.2	./ext/cargo-vendor/wasm-bindgen-0.2.89/guide/src/reference/types/result.md
wasmtime-20.0.0	./ext/cargo-vendor/wasm-bindgen-0.2.89/guide/src/reference/types/result.md
wasmtime-18.0.3	./ext/cargo-vendor/wasm-bindgen-0.2.89/guide/src/reference/types/result.md
wasmtime-17.0.1	./ext/cargo-vendor/wasm-bindgen-0.2.89/guide/src/reference/types/result.md
wasmtime-17.0.0	./ext/cargo-vendor/wasm-bindgen-0.2.89/guide/src/reference/types/result.md
wasmtime-16.0.0	./ext/cargo-vendor/wasm-bindgen-0.2.89/guide/src/reference/types/result.md
wasmtime-15.0.1	./ext/cargo-vendor/wasm-bindgen-0.2.89/guide/src/reference/types/result.md
wasmtime-15.0.0	./ext/cargo-vendor/wasm-bindgen-0.2.89/guide/src/reference/types/result.md
wasmtime-14.0.4	./ext/cargo-vendor/wasm-bindgen-0.2.87/guide/src/reference/types/result.md
wasmtime-14.0.3	./ext/cargo-vendor/wasm-bindgen-0.2.87/guide/src/reference/types/result.md
wasmtime-14.0.1	./ext/cargo-vendor/wasm-bindgen-0.2.87/guide/src/reference/types/result.md
wasmtime-14.0.0	./ext/cargo-vendor/wasm-bindgen-0.2.87/guide/src/reference/types/result.md
wasmtime-13.0.0	./ext/cargo-vendor/wasm-bindgen-0.2.87/guide/src/reference/types/result.md
wasmtime-12.0.1	./ext/cargo-vendor/wasm-bindgen-0.2.87/guide/src/reference/types/result.md
wasmtime-12.0.0	./ext/cargo-vendor/wasm-bindgen-0.2.87/guide/src/reference/types/result.md
wasmtime-11.0.0	./ext/cargo-vendor/wasm-bindgen-0.2.87/guide/src/reference/types/result.md
wasmtime-10.0.1	./ext/cargo-vendor/wasm-bindgen-0.2.87/guide/src/reference/types/result.md