[][src]Struct js_sys::Promise

#[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

Methods

impl Promise
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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

impl Promise
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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

impl Promise
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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

impl Promise
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The Promise.reject(reason) method returns a Promise object that is rejected with the given reason.

MDN documentation

impl Promise
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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

impl Promise
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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

impl Promise
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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

impl Promise
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Same as then, only with both arguments provided.

impl Promise
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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

Methods from Deref<Target = Object>

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 toString() method returns a string representing the object.

MDN documentation

The valueOf() method returns the primitive value of the specified object.

MDN documentation

Trait Implementations

impl AsRef<JsValue> for Promise
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impl AsRef<Object> for Promise
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impl From<JsValue> for Promise
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impl From<Promise> for JsValue
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impl From<Promise> for Object
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impl Clone for Promise
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Performs copy-assignment from source. Read more

impl Debug for Promise
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impl Deref for Promise
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The resulting type after dereferencing.

impl WasmDescribe for Promise
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impl IntoWasmAbi for Promise
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The wasm ABI type that this converts into when crossing the ABI boundary. Read more

impl<'a> IntoWasmAbi for &'a Promise
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The wasm ABI type that this converts into when crossing the ABI boundary. Read more

impl FromWasmAbi for Promise
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The wasm ABI type that this converts from when coming back out from the ABI boundary. Read more

impl OptionFromWasmAbi for Promise
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impl RefFromWasmAbi for Promise
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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

impl OptionIntoWasmAbi for Promise
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impl<'a> OptionIntoWasmAbi for &'a Promise
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impl JsCast for Promise
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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

Auto Trait Implementations

impl !Send for Promise

impl !Sync for Promise

Blanket Implementations

impl<T> ToOwned for T where
    T: Clone
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impl<T> From for T
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impl<T, U> Into for T where
    U: From<T>, 
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impl<T, U> TryFrom for T where
    T: From<U>, 
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🔬 This is a nightly-only experimental API. (try_from)

The type returned in the event of a conversion error.

impl<T> Borrow for T where
    T: ?Sized
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impl<T, U> TryInto for T where
    U: TryFrom<T>, 
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🔬 This is a nightly-only experimental API. (try_from)

The type returned in the event of a conversion error.

impl<T> BorrowMut for T where
    T: ?Sized
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impl<T> Any for T where
    T: 'static + ?Sized
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impl<T> ReturnWasmAbi for T where
    T: IntoWasmAbi
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Same as IntoWasmAbi::Abi