pub struct Promise { /* private fields */ }
Expand description
The Promise
object represents the eventual completion (or failure) of
an asynchronous operation, and its resulting value.
Implementations§
source§impl Promise
impl Promise
sourcepub fn new(cb: &mut dyn FnMut(Function, Function)) -> Promise
pub fn new(cb: &mut dyn FnMut(Function, Function)) -> Promise
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.
source§impl Promise
impl Promise
source§impl Promise
impl Promise
sourcepub fn all_settled(obj: &JsValue) -> Promise
pub fn all_settled(obj: &JsValue) -> Promise
The Promise.allSettled(iterable)
method returns a single Promise
that
resolves when all of the promises in the iterable argument have either
fulfilled or rejected or when the iterable argument contains no promises.
source§impl Promise
impl Promise
sourcepub fn any(obj: &JsValue) -> Promise
pub fn any(obj: &JsValue) -> Promise
The Promise.any(iterable)
method returns a single Promise
that
resolves when any of the promises in the iterable argument have resolved
or when the iterable argument contains no promises. It rejects with an
AggregateError
if all promises in the iterable rejected.
source§impl Promise
impl Promise
source§impl Promise
impl Promise
source§impl Promise
impl Promise
sourcepub fn resolve(obj: &JsValue) -> Promise
pub fn resolve(obj: &JsValue) -> Promise
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.
source§impl Promise
impl Promise
sourcepub fn catch(&self, cb: &Closure<dyn FnMut(JsValue)>) -> Promise
pub fn catch(&self, cb: &Closure<dyn FnMut(JsValue)>) -> Promise
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)
).
source§impl Promise
impl Promise
sourcepub fn finally(&self, cb: &Closure<dyn FnMut()>) -> Promise
pub fn finally(&self, cb: &Closure<dyn FnMut()>) -> Promise
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.
Methods from Deref<Target = Object>§
sourcepub fn constructor(&self) -> Function
pub fn constructor(&self) -> Function
The constructor property returns a reference to the Object
constructor
function that created the instance object.
sourcepub fn has_own_property(&self, property: &JsValue) -> bool
pub fn has_own_property(&self, property: &JsValue) -> bool
The hasOwnProperty()
method returns a boolean indicating whether the
object has the specified property as its own property (as opposed to
inheriting it).
sourcepub fn is_prototype_of(&self, value: &JsValue) -> bool
pub fn is_prototype_of(&self, value: &JsValue) -> bool
The isPrototypeOf()
method checks if an object exists in another
object’s prototype chain.
sourcepub fn property_is_enumerable(&self, property: &JsValue) -> bool
pub fn property_is_enumerable(&self, property: &JsValue) -> bool
The propertyIsEnumerable()
method returns a Boolean indicating
whether the specified property is enumerable.
sourcepub fn to_locale_string(&self) -> JsString
pub fn to_locale_string(&self) -> JsString
The toLocaleString()
method returns a string representing the object.
This method is meant to be overridden by derived objects for
locale-specific purposes.
sourcepub fn to_string(&self) -> JsString
pub fn to_string(&self) -> JsString
The toString()
method returns a string representing the object.
Methods from Deref<Target = JsValue>§
pub const NULL: JsValue = _
pub const UNDEFINED: JsValue = _
pub const TRUE: JsValue = _
pub const FALSE: JsValue = _
sourcepub fn as_f64(&self) -> Option<f64>
pub fn as_f64(&self) -> Option<f64>
Returns the f64
value of this JS value if it’s an instance of a
number.
If this JS value is not an instance of a number then this returns
None
.
sourcepub fn as_string(&self) -> Option<String>
pub fn as_string(&self) -> Option<String>
If this JS value is a string value, this function copies the JS string
value into Wasm linear memory, encoded as UTF-8, and returns it as a
Rust String
.
To avoid the copying and re-encoding, consider the
JsString::try_from()
function from js-sys
instead.
If this JS value is not an instance of a string or if it’s not valid
utf-8 then this returns None
.
§UTF-16 vs UTF-8
JavaScript strings in general are encoded as UTF-16, but Rust strings
are encoded as UTF-8. This can cause the Rust string to look a bit
different than the JS string sometimes. For more details see the
documentation about the str
type which contains a few
caveats about the encodings.
sourcepub fn as_bool(&self) -> Option<bool>
pub fn as_bool(&self) -> Option<bool>
Returns the bool
value of this JS value if it’s an instance of a
boolean.
If this JS value is not an instance of a boolean then this returns
None
.
sourcepub fn is_undefined(&self) -> bool
pub fn is_undefined(&self) -> bool
Tests whether this JS value is undefined
sourcepub fn is_function(&self) -> bool
pub fn is_function(&self) -> bool
Tests whether the type of this JS value is function
.
sourcepub fn js_in(&self, obj: &JsValue) -> bool
pub fn js_in(&self, obj: &JsValue) -> bool
Applies the binary in
JS operator on the two JsValue
s.
sourcepub fn loose_eq(&self, other: &JsValue) -> bool
pub fn loose_eq(&self, other: &JsValue) -> bool
Compare two JsValue
s for equality, using the ==
operator in JS.
sourcepub fn unsigned_shr(&self, rhs: &JsValue) -> u32
pub fn unsigned_shr(&self, rhs: &JsValue) -> u32
Applies the binary >>>
JS operator on the two JsValue
s.
sourcepub fn checked_div(&self, rhs: &JsValue) -> JsValue
pub fn checked_div(&self, rhs: &JsValue) -> JsValue
Applies the binary /
JS operator on two JsValue
s, catching and returning any RangeError
thrown.
sourcepub fn pow(&self, rhs: &JsValue) -> JsValue
pub fn pow(&self, rhs: &JsValue) -> JsValue
Applies the binary **
JS operator on the two JsValue
s.
sourcepub fn lt(&self, other: &JsValue) -> bool
pub fn lt(&self, other: &JsValue) -> bool
Applies the binary <
JS operator on the two JsValue
s.
sourcepub fn le(&self, other: &JsValue) -> bool
pub fn le(&self, other: &JsValue) -> bool
Applies the binary <=
JS operator on the two JsValue
s.
sourcepub fn ge(&self, other: &JsValue) -> bool
pub fn ge(&self, other: &JsValue) -> bool
Applies the binary >=
JS operator on the two JsValue
s.
sourcepub fn gt(&self, other: &JsValue) -> bool
pub fn gt(&self, other: &JsValue) -> bool
Applies the binary >
JS operator on the two JsValue
s.
sourcepub fn unchecked_into_f64(&self) -> f64
pub fn unchecked_into_f64(&self) -> f64
Applies the unary +
JS operator on a JsValue
. Can throw.
Trait Implementations§
source§impl FromWasmAbi for Promise
impl FromWasmAbi for Promise
source§impl<'a> IntoWasmAbi for &'a Promise
impl<'a> IntoWasmAbi for &'a Promise
source§impl IntoWasmAbi for Promise
impl IntoWasmAbi for Promise
source§impl JsCast for Promise
impl JsCast for Promise
source§fn instanceof(val: &JsValue) -> bool
fn instanceof(val: &JsValue) -> bool
instanceof
check to see whether the JsValue
provided is an instance of this type. Read moresource§fn unchecked_from_js(val: JsValue) -> Promise
fn unchecked_from_js(val: JsValue) -> Promise
source§fn unchecked_from_js_ref(val: &JsValue) -> &Promise
fn unchecked_from_js_ref(val: &JsValue) -> &Promise
source§fn has_type<T>(&self) -> boolwhere
T: JsCast,
fn has_type<T>(&self) -> boolwhere
T: JsCast,
T
. Read moresource§fn dyn_into<T>(self) -> Result<T, Self>where
T: JsCast,
fn dyn_into<T>(self) -> Result<T, Self>where
T: JsCast,
T
. Read moresource§fn dyn_ref<T>(&self) -> Option<&T>where
T: JsCast,
fn dyn_ref<T>(&self) -> Option<&T>where
T: JsCast,
T
. Read moresource§fn unchecked_into<T>(self) -> Twhere
T: JsCast,
fn unchecked_into<T>(self) -> Twhere
T: JsCast,
source§fn unchecked_ref<T>(&self) -> &Twhere
T: JsCast,
fn unchecked_ref<T>(&self) -> &Twhere
T: JsCast,
source§impl LongRefFromWasmAbi for Promise
impl LongRefFromWasmAbi for Promise
source§unsafe fn long_ref_from_abi(
js: <Promise as LongRefFromWasmAbi>::Abi,
) -> <Promise as LongRefFromWasmAbi>::Anchor
unsafe fn long_ref_from_abi( js: <Promise as LongRefFromWasmAbi>::Abi, ) -> <Promise as LongRefFromWasmAbi>::Anchor
RefFromWasmAbi::ref_from_abi
source§impl OptionFromWasmAbi for Promise
impl OptionFromWasmAbi for Promise
source§impl<'a> OptionIntoWasmAbi for &'a Promise
impl<'a> OptionIntoWasmAbi for &'a Promise
source§impl OptionIntoWasmAbi for Promise
impl OptionIntoWasmAbi for Promise
source§impl RefFromWasmAbi for Promise
impl RefFromWasmAbi for Promise
source§type Abi = <JsValue as RefFromWasmAbi>::Abi
type Abi = <JsValue as RefFromWasmAbi>::Abi
Self
are recovered from.source§type Anchor = ManuallyDrop<Promise>
type Anchor = ManuallyDrop<Promise>
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.source§unsafe fn ref_from_abi(
js: <Promise as RefFromWasmAbi>::Abi,
) -> <Promise as RefFromWasmAbi>::Anchor
unsafe fn ref_from_abi( js: <Promise as RefFromWasmAbi>::Abi, ) -> <Promise as RefFromWasmAbi>::Anchor
Auto Trait Implementations§
impl Freeze for Promise
impl RefUnwindSafe for Promise
impl !Send for Promise
impl !Sync for Promise
impl Unpin for Promise
impl UnwindSafe for Promise
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
source§impl<T> CloneToUninit for Twhere
T: Clone,
impl<T> CloneToUninit for Twhere
T: Clone,
source§unsafe fn clone_to_uninit(&self, dst: *mut T)
unsafe fn clone_to_uninit(&self, dst: *mut T)
clone_to_uninit
)source§impl<T> ReturnWasmAbi for Twhere
T: IntoWasmAbi,
impl<T> ReturnWasmAbi for Twhere
T: IntoWasmAbi,
source§type Abi = <T as IntoWasmAbi>::Abi
type Abi = <T as IntoWasmAbi>::Abi
IntoWasmAbi::Abi
source§fn return_abi(self) -> <T as ReturnWasmAbi>::Abi
fn return_abi(self) -> <T as ReturnWasmAbi>::Abi
IntoWasmAbi::into_abi
, except that it may throw and never
return in the case of Err
.