Trait wasm_bindgen::UnwrapThrowExt
source · pub trait UnwrapThrowExt<T>: Sized {
// Required method
fn expect_throw(self, message: &str) -> T;
// Provided method
fn unwrap_throw(self) -> T { ... }
}
Expand description
An extension trait for Option<T>
and Result<T, E>
for unwrapping the T
value, or throwing a JS error if it is not available.
These methods should have a smaller code size footprint than the normal
Option::unwrap
and Option::expect
methods, but they are specific to
working with wasm and JS.
On non-wasm32 targets, defaults to the normal unwrap/expect calls.
Example
use wasm_bindgen::prelude::*;
// If the value is `Option::Some` or `Result::Ok`, then we just get the
// contained `T` value.
let x = Some(42);
assert_eq!(x.unwrap_throw(), 42);
let y: Option<i32> = None;
// This call would throw an error to JS!
//
// y.unwrap_throw()
//
// And this call would throw an error to JS with a custom error message!
//
// y.expect_throw("woopsie daisy!")
Required Methods§
sourcefn expect_throw(self, message: &str) -> T
fn expect_throw(self, message: &str) -> T
Unwrap this container’s T
value, or throw an error to JS with the
given message if the T
value is unavailable (e.g. an Option<T>
is
None
).
Provided Methods§
sourcefn unwrap_throw(self) -> T
fn unwrap_throw(self) -> T
Unwrap this Option
or Result
, but instead of panicking on failure,
throw an exception to JavaScript.