#[repr(transparent)]
pub struct Promise { /* fields omitted */ }
The Promise
object represents the eventual completion (or failure) of
an asynchronous operation, and its resulting value.
MDN documentation
Creates a new Promise
with the provided executor cb
The cb
is a function that is passed with the arguments resolve
and
reject
. The cb
function is executed immediately by the Promise
implementation, passing resolve
and reject
functions (the executor
is called before the Promise
constructor even returns the created
object). The resolve
and reject
functions, when called, resolve or
reject the promise, respectively. The executor normally initiates
some asynchronous work, and then, once that completes, either calls
the resolve
function to resolve the promise or else rejects it if an
error occurred.
If an error is thrown in the executor function, the promise is rejected.
The return value of the executor is ignored.
MDN documentation
The Promise.all(iterable)
method returns a single Promise
that
resolves when all of the promises in the iterable argument have resolved
or when the iterable argument contains no promises. It rejects with the
reason of the first promise that rejects.
MDN documentation
The Promise.race(iterable)
method returns a promise that resolves or
rejects as soon as one of the promises in the iterable resolves or
rejects, with the value or reason from that promise.
MDN documentation
The Promise.reject(reason)
method returns a Promise
object that is
rejected with the given reason.
MDN documentation
The Promise.resolve(value)
method returns a Promise
object that is
resolved with the given value. If the value is a promise, that promise
is returned; if the value is a thenable (i.e. has a "then" method), the
returned promise will "follow" that thenable, adopting its eventual
state; otherwise the returned promise will be fulfilled with the value.
MDN documentation
The catch()
method returns a Promise
and deals with rejected cases
only. It behaves the same as calling Promise.prototype.then(undefined, onRejected)
(in fact, calling obj.catch(onRejected)
internally calls
obj.then(undefined, onRejected)
).
MDN documentation
The then()
method returns a Promise
. It takes up to two arguments:
callback functions for the success and failure cases of the Promise
.
MDN documentation
Same as then
, only with both arguments provided.
The finally()
method returns a Promise
. When the promise is settled,
whether fulfilled or rejected, the specified callback function is
executed. This provides a way for code that must be executed once the
Promise
has been dealt with to be run whether the promise was
fulfilled successfully or rejected.
This lets you avoid duplicating code in both the promise's then()
and
catch()
handlers.
MDN documentation
The hasOwnProperty()
method returns a boolean indicating whether the
object has the specified property as its own property (as opposed to
inheriting it).
MDN documentation
The isPrototypeOf()
method checks if an object exists in another
object's prototype chain.
MDN documentation
The propertyIsEnumerable()
method returns a Boolean indicating
whether the specified property is enumerable.
MDN documentation
The toLocaleString()
method returns a string representing the object.
This method is meant to be overridden by derived objects for
locale-specific purposes.
MDN documentation
The valueOf()
method returns the primitive value of the
specified object.
MDN documentation
Performs copy-assignment from source
. Read more
Formats the value using the given formatter. Read more
The resulting type after dereferencing.
The wasm ABI type that this converts into when crossing the ABI boundary. Read more
Convert self
into Self::Abi
so that it can be sent across the wasm ABI boundary. Read more
The wasm ABI type that this converts into when crossing the ABI boundary. Read more
Convert self
into Self::Abi
so that it can be sent across the wasm ABI boundary. Read more
The wasm ABI type that this converts from when coming back out from the ABI boundary. Read more
Tests whether the argument is a "none" instance. If so it will be deserialized as None
, and otherwise it will be passed to FromWasmAbi
. Read more
The wasm ABI type references to Self
are recovered from.
The type that holds the reference to Self
for the duration of the invocation of the function that has an &Self
parameter. This is required to ensure that the lifetimes don't persist beyond one function call, and so that they remain anonymous. Read more
Recover a Self::Anchor
from Self::Abi
. Read more
Returns an ABI instance indicating "none", which JS will interpret as the None
branch of this option. Read more
Returns an ABI instance indicating "none", which JS will interpret as the None
branch of this option. Read more
Performs a dynamic instanceof
check to see whether the JsValue
provided is an instance of this type. Read more
Performs a zero-cost unchecked conversion from a JsValue
into an instance of Self
Read more
Performs a zero-cost unchecked conversion from a &JsValue
into an instance of &Self
. Read more
Test whether this JS value is an instance of the type T
. Read more
Performs a dynamic cast (checked at runtime) of this value into the target type T
. Read more
Performs a dynamic cast (checked at runtime) of this value into the target type T
. Read more
Performs a zero-cost unchecked cast into the specified type. Read more
Performs a zero-cost unchecked cast into a reference to the specified type. Read more
Creates owned data from borrowed data, usually by cloning. Read more
🔬 This is a nightly-only experimental API. (toowned_clone_into
)
recently added
Uses borrowed data to replace owned data, usually by cloning. Read more
🔬 This is a nightly-only experimental API. (try_from
)
The type returned in the event of a conversion error.
🔬 This is a nightly-only experimental API. (try_from
)
Immutably borrows from an owned value. Read more
🔬 This is a nightly-only experimental API. (try_from
)
The type returned in the event of a conversion error.
🔬 This is a nightly-only experimental API. (try_from
)
Mutably borrows from an owned value. Read more
🔬 This is a nightly-only experimental API. (get_type_id
)
this method will likely be replaced by an associated static
Same as IntoWasmAbi::into_abi
, except that it may throw and never return in the case of Err
. Read more