Struct Promise 

pub struct Promise<T = JsValue> { /* private fields */ }

The Promise object represents the eventual completion (or failure) of an asynchronous operation, and its resulting value.

MDN documentation

Implementations

impl Promise

pub fn new(cb: &mut dyn FnMut(Function, Function)) -> Promise

impl Promise

pub fn new_typed<T: Promising + JsGeneric>( cb: &mut dyn FnMut(Function<fn(T) -> Undefined>, Function<fn(JsValue) -> Undefined>), ) -> Promise<<T as Promising>::Resolution>

where dyn FnMut(Function<fn(T) -> Undefined>, Function<fn(JsValue) -> Undefined>): ErasableGenericBorrowMut<dyn FnMut(Function<fn(JsValue) -> Undefined>, Function<fn(JsValue) -> Undefined>)>, for<'__wry_bindgen> &'__wry_bindgen mut dyn FnMut(Function<fn(T) -> Undefined>, Function<fn(JsValue) -> Undefined>): EncodeTypeDef + BinaryEncode, Promise<<T as Promising>::Resolution>: ErasableGenericOwn<Promise<<JsValue as Promising>::Resolution>> + EncodeTypeDef + BatchableResult,

impl Promise

pub fn all(obj: &JsValue) -> Promise

impl Promise

pub fn all_iterable<I>( obj: &I, ) -> Promise<Array<<I::Item as Promising>::Resolution>>

where I::Item: Promising, I: ErasableGenericBorrow<JsValue> + EncodeTypeDef + Iterable, for<'__wry_bindgen> &'__wry_bindgen I: BinaryEncode, Promise<Array<<I::Item as Promising>::Resolution>>: ErasableGenericOwn<Promise<Array<<JsValue as Promising>::Resolution>>> + EncodeTypeDef + BatchableResult,

impl Promise

pub fn all_settled(obj: &JsValue) -> Promise

impl Promise

pub fn all_settled_iterable<I>( obj: &I, ) -> Promise<Array<PromiseState<<I::Item as Promising>::Resolution>>>

where I::Item: Promising, I: ErasableGenericBorrow<JsValue> + EncodeTypeDef + Iterable, for<'__wry_bindgen> &'__wry_bindgen I: BinaryEncode, Promise<Array<PromiseState<<I::Item as Promising>::Resolution>>>: ErasableGenericOwn<Promise<Array<PromiseState<<JsValue as Promising>::Resolution>>>> + EncodeTypeDef + BatchableResult,

impl Promise

pub fn any(obj: &JsValue) -> Promise

impl Promise

pub fn any_iterable<I>(obj: &I) -> Promise<<I::Item as Promising>::Resolution>

where I::Item: Promising, I: ErasableGenericBorrow<JsValue> + EncodeTypeDef + Iterable, for<'__wry_bindgen> &'__wry_bindgen I: BinaryEncode, Promise<<I::Item as Promising>::Resolution>: ErasableGenericOwn<Promise<<JsValue as Promising>::Resolution>> + EncodeTypeDef + BatchableResult,

impl Promise

pub fn race(obj: &JsValue) -> Promise

impl Promise

pub fn race_iterable<I>(obj: &I) -> Promise<<I::Item as Promising>::Resolution>

where I::Item: Promising, I: ErasableGenericBorrow<JsValue> + EncodeTypeDef + Iterable, for<'__wry_bindgen> &'__wry_bindgen I: BinaryEncode, Promise<<I::Item as Promising>::Resolution>: ErasableGenericOwn<Promise<<JsValue as Promising>::Resolution>> + EncodeTypeDef + BatchableResult,

impl Promise

pub fn reject(obj: &JsValue) -> Promise

impl Promise

pub fn reject_typed<T>(obj: &JsValue) -> Promise<T>

where Promise<T>: ErasableGenericOwn<Promise<JsValue>> + EncodeTypeDef + BatchableResult,

impl Promise

pub fn resolve<U>(obj: &U) -> Promise<U::Resolution>

where U: ErasableGenericBorrow<JsValue> + EncodeTypeDef + Promising, for<'__wry_bindgen> &'__wry_bindgen U: BinaryEncode, Promise<U::Resolution>: ErasableGenericOwn<Promise<JsValue>> + EncodeTypeDef + BatchableResult,

impl<T> Promise<T>

pub fn catch( &self, cb: &ScopedClosure<'_, dyn FnMut(JsValue)>, ) -> Promise<JsValue>

impl<T> Promise<T>

pub fn catch_map<'a, R: Promising>( &self, cb: &ScopedClosure<'a, dyn FnMut(T) -> Result<R, JsError>>, ) -> Promise<R::Resolution>

where ScopedClosure<'a, dyn FnMut(T) -> Result<R, JsError>>: ErasableGenericBorrow<ScopedClosure<'static, dyn FnMut(JsValue) -> Result<JsValue, JsError>>>, Promise<R::Resolution>: ErasableGenericOwn<Promise<JsValue>> + EncodeTypeDef + BatchableResult,

impl<T> Promise<T>

pub fn then<'a>(&self, cb: &ScopedClosure<'a, dyn FnMut(T)>) -> Promise<JsValue>

where ScopedClosure<'a, dyn FnMut(T)>: ErasableGenericBorrow<ScopedClosure<'static, dyn FnMut(JsValue)>>,

impl<T> Promise<T>

pub fn then_with_reject<'a, R: Promising>( &self, resolve: &ScopedClosure<'a, dyn FnMut(T) -> Result<R, JsError>>, reject: &ScopedClosure<'a, dyn FnMut(JsValue) -> Result<R, JsError>>, ) -> Promise<R::Resolution>

where ScopedClosure<'a, dyn FnMut(T) -> Result<R, JsError>>: ErasableGenericBorrow<ScopedClosure<'static, dyn FnMut(JsValue) -> Result<JsValue, JsError>>>, ScopedClosure<'a, dyn FnMut(JsValue) -> Result<R, JsError>>: ErasableGenericBorrow<ScopedClosure<'static, dyn FnMut(JsValue) -> Result<JsValue, JsError>>>, Promise<R::Resolution>: ErasableGenericOwn<Promise<JsValue>> + EncodeTypeDef + BatchableResult,

impl<T> Promise<T>

pub fn then_map<'a, R: Promising>( &self, cb: &ScopedClosure<'a, dyn FnMut(T) -> Result<R, JsError>>, ) -> Promise<R::Resolution>

where ScopedClosure<'a, dyn FnMut(T) -> Result<R, JsError>>: ErasableGenericBorrow<ScopedClosure<'static, dyn FnMut(JsValue) -> Result<JsValue, JsError>>>, Promise<R::Resolution>: ErasableGenericOwn<Promise<JsValue>> + EncodeTypeDef + BatchableResult,

impl Promise

pub fn then2( &self, resolve: &ScopedClosure<'_, dyn FnMut(JsValue)>, reject: &ScopedClosure<'_, dyn FnMut(JsValue)>, ) -> Promise

impl<T> Promise<T>

pub fn finally(&self, cb: &ScopedClosure<'_, dyn FnMut()>) -> Promise<JsValue>

impl Promise

pub fn all_tuple<T: PromiseTuple>(promises: T) -> Promise<T::Joined>

Heterogeneous counterpart to Promise::all_iterable: accepts a Rust tuple of Promise<T_i> and returns a single Promise resolving to a typed ArrayTuple<(T_1, T_2, ..., T_n)>.

Destructure the awaited result via ArrayTuple::into_tuple to get the individual values back as a native Rust tuple. Implemented for arity 1..=8.

Rejects with the first rejection, matching Promise.all semantics.

Example

use js_sys::Promise;

let (response, buffer) = Promise::all_tuple((fetch_promise, buffer_promise))
    .await?
    .into_tuple();

pub fn all_settled_tuple<T: PromiseTuple>(promises: T) -> Promise<T::Settled>

Heterogeneous counterpart to Promise::all_settled_iterable: accepts a Rust tuple of Promise<T_i> and returns a single Promise resolving to a typed ArrayTuple<(PromiseState<T_1>, ..., PromiseState<T_n>)>.

Unlike Promise::all_tuple, this never rejects early: every input settles (fulfills or rejects) and is reflected by its PromiseState slot in the result tuple. Implemented for arity 1..=8.

Example

use js_sys::Promise;

let results = Promise::all_settled_tuple((fetch_promise, buffer_promise)).await?;
let (response_state, buffer_state) = results.into_tuple();

Methods from Deref<Target = Object>

pub fn constructor(&self) -> Function

pub fn has_own_property(&self, property: &JsValue) -> bool

👎Deprecated:

Use Object::hasOwn instead.

pub fn is_prototype_of(&self, value: &JsValue) -> bool

pub fn property_is_enumerable(&self, property: &JsValue) -> bool

pub fn to_locale_string(&self) -> JsString

pub fn to_string(&self) -> JsString

pub fn to_js_string(&self) -> JsString

pub fn value_of(&self) -> Object

Methods from Deref<Target = JsValue>

pub const NULL: JsValue

pub const UNDEFINED: JsValue

pub const TRUE: JsValue

pub const FALSE: JsValue

pub fn unchecked_into_f64(&self) -> f64

Returns the value as f64 without type checking. Used by serde-wasm-bindgen for numeric conversions.

pub fn has_type<T>(&self) -> bool

where T: JsCast,

Check if this value is an instance of a specific JS type.

pub fn checked_div(&self, rhs: &JsValue) -> JsValue

Checked division.

pub fn pow(&self, rhs: &JsValue) -> JsValue

Power operation.

pub fn bit_and(&self, rhs: &JsValue) -> JsValue

Bitwise AND.

pub fn bit_or(&self, rhs: &JsValue) -> JsValue

Bitwise OR.

pub fn bit_xor(&self, rhs: &JsValue) -> JsValue

Bitwise XOR.

pub fn bit_not(&self) -> JsValue

Bitwise NOT.

pub fn shl(&self, rhs: &JsValue) -> JsValue

Left shift.

pub fn shr(&self, rhs: &JsValue) -> JsValue

Signed right shift.

pub fn unsigned_shr(&self, rhs: &JsValue) -> u32

Unsigned right shift.

pub fn add(&self, rhs: &JsValue) -> JsValue

Add.

pub fn sub(&self, rhs: &JsValue) -> JsValue

Subtract.

pub fn mul(&self, rhs: &JsValue) -> JsValue

Multiply.

pub fn div(&self, rhs: &JsValue) -> JsValue

Divide.

pub fn rem(&self, rhs: &JsValue) -> JsValue

Remainder.

pub fn neg(&self) -> JsValue

Negate.

pub fn lt(&self, other: &JsValue) -> bool

Less than comparison.

pub fn le(&self, other: &JsValue) -> bool

Less than or equal comparison.

pub fn gt(&self, other: &JsValue) -> bool

Greater than comparison.

pub fn ge(&self, other: &JsValue) -> bool

Greater than or equal comparison.

pub fn loose_eq(&self, other: &JsValue) -> bool

Loose equality (==).

pub fn is_falsy(&self) -> bool

Check if this value is a falsy value in JavaScript.

pub fn is_truthy(&self) -> bool

Check if this value is a truthy value in JavaScript.

pub fn is_object(&self) -> bool

Check if this value is an object.

pub fn is_function(&self) -> bool

Check if this value is a function.

pub fn is_string(&self) -> bool

Check if this value is a string.

pub fn is_symbol(&self) -> bool

Check if this value is a symbol.

pub fn is_bigint(&self) -> bool

Check if this value is a bigint.

pub fn is_array(&self) -> bool

Check if this value is an Array.

pub fn is_undefined(&self) -> bool

Check if this value is undefined.

pub fn is_null(&self) -> bool

Check if this value is null.

pub fn is_null_or_undefined(&self) -> bool

Check if this value is null or undefined.

pub fn js_typeof(&self) -> JsValue

Get the typeof this value as a string.

pub fn js_in(&self, obj: &JsValue) -> bool

Check if this value has a property with the given name.

pub fn as_bool(&self) -> Option<bool>

Get the value as a bool.

pub fn as_f64(&self) -> Option<f64>

Get the value as an f64.

pub fn as_string(&self) -> Option<String>

Get the value as a string.

pub fn as_debug_string(&self) -> String

Get a debug string representation of the value.

Trait Implementations

impl<T> AsRef<JsValue> for Promise<T>

fn as_ref(&self) -> &JsValue

Converts this type into a shared reference of the (usually inferred) input type.

impl<T> AsRef<Object> for Promise<T>

fn as_ref(&self) -> &Object

Converts this type into a shared reference of the (usually inferred) input type.

impl<T> AsRef<Promise<T>> for Promise<T>

fn as_ref(&self) -> &Promise<T>

Converts this type into a shared reference of the (usually inferred) input type.

impl<T> BatchableResult for Promise<T>

fn try_placeholder(batch: &mut Runtime<'_>) -> Option<Self>

impl<T> BinaryDecode for Promise<T>

fn decode(decoder: &mut DecodedData<'_>) -> Result<Self, DecodeError>

impl<T> BinaryEncode for Promise<T>

fn encode(self, encoder: &mut EncodedData)

impl<T: Clone> Clone for Promise<T>

fn clone(&self) -> Promise<T>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for Promise<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Deref for Promise<T>

type Target = Object

The resulting type after dereferencing.

fn deref(&self) -> &Object

Dereferences the value.

impl<T> EncodeTypeDef for Promise<T>

fn encode_type_def(type_def: &mut TypeDef)

impl<T> ErasableGeneric for Promise<T>

type Repr = JsValue

impl<T> From<JsValue> for Promise<T>

fn from(val: JsValue) -> Self

Converts to this type from the input type.

impl<T> From<Promise<T>> for JsValue

fn from(val: Promise<T>) -> Self

Converts to this type from the input type.

impl<T> From<Promise<T>> for Object

fn from(val: Promise<T>) -> Object

Converts to this type from the input type.

impl<T: FromWasmAbi + 'static> From<Promise<T>> for JsFuture<T>

fn from(js: Promise<T>) -> JsFuture<T>

Converts to this type from the input type.

impl<T: FromWasmAbi + 'static> IntoFuture for Promise<T>

type Output = Result<T, JsValue>

The output that the future will produce on completion.

type IntoFuture = JsFuture<T>

Which kind of future are we turning this into?

fn into_future(self) -> JsFuture<T>

Creates a future from a value.

impl<T: 'static> IntoJsGeneric for Promise<T>

where Promise<T>: JsGeneric,

type JsCanon = Promise<T>

fn to_js(self) -> Self::JsCanon

impl<T> JsCast for Promise<T>

fn instanceof(__val: &JsValue) -> bool

Check if a JsValue is an instance of this type.

fn unchecked_from_js(val: JsValue) -> Self

Unchecked cast from JsValue to this type.

fn unchecked_from_js_ref(val: &JsValue) -> &Self

Unchecked cast from a JsValue reference to a reference of this type.

fn is_type_of(val: &JsValue) -> bool

Performs a dynamic type check to see whether the JsValue provided is a value of this type.

fn has_type<T>(&self) -> bool

where T: JsCast,

Test whether this JS value has a type T.

fn dyn_into<T>(self) -> Result<T, Self>

where T: JsCast,

Try to cast this value to type T.

fn dyn_ref<T>(&self) -> Option<&T>

where T: JsCast,

Try to get a reference to type T from this value.

fn is_instance_of<T>(&self) -> bool

where T: JsCast,

Test whether this JS value is an instance of the type T.

fn unchecked_into<T>(self) -> T

where T: JsCast,

Unchecked cast to another type.

fn unchecked_ref<T>(&self) -> &T

where T: JsCast,

Unchecked cast to a reference of another type.

impl<T> JsRefEncode for Promise<T>

fn js_ref(&self) -> JsRef

impl<T: JsGeneric> Promising for Promise<T>

type Resolution = T

impl<T> UpcastFrom<Promise<T>> for JsValue

impl<T> UpcastFrom<Promise<T>> for JsOption<JsValue>

impl<T, __WryUpcastTarget0> UpcastFrom<Promise<T>> for Promise<__WryUpcastTarget0>

where __WryUpcastTarget0: UpcastFrom<T>,

impl<T, __WryUpcastTarget0> UpcastFrom<Promise<T>> for JsOption<Promise<__WryUpcastTarget0>>

where __WryUpcastTarget0: UpcastFrom<T>,

impl<T> UpcastFrom<Promise<T>> for Object

impl<T> UpcastFrom<Promise<T>> for JsOption<Object>