Promise in js_sys - Rust (original) (raw)
pub struct Promise<T = JsValue> { /* private fields */ }Expand description
The Promise object represents the eventual completion (or failure) of an asynchronous operation, and its resulting value.
Creates a new Promise with the provided executor cb
The cb is a function that is passed with the arguments resolve andreject. The cb function is executed immediately by the Promiseimplementation, 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.
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.
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.
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.
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.
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 anAggregateError if all promises in the iterable rejected.
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 anAggregateError if all promises in the iterable rejected.
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.
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.
The Promise.reject(reason) method returns a Promise object that is rejected with the given reason.
The Promise.reject(reason) method returns a Promise object that is rejected with the given reason.
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.
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 callsobj.then(undefined, onRejected)).
Same as catch, but returning a result to become the new Promise value.
The then() method returns a Promise. It takes up to two arguments: callback functions for the success and failure cases of the Promise.
The then() method returns a Promise. It takes up to two arguments: callback functions for the success and failure cases of the Promise.
Alias for then() with a return value. The then() method returns a Promise. It takes up to two arguments: callback functions for the success and failure cases of the 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 thePromise 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() andcatch() handlers.
The constructor property returns a reference to the Object constructor function that created the instance object.
👎Deprecated: Use Object::hasOwn instead.
The hasOwnProperty() method returns a boolean indicating whether the object has the specified property as its own property (as opposed to inheriting it).
The isPrototypeOf() method checks if an object exists in another object’s prototype chain.
The propertyIsEnumerable() method returns a Boolean indicating whether the specified property is enumerable.
The toLocaleString() method returns a string representing the object. This method is meant to be overridden by derived objects for locale-specific purposes.
The valueOf() method returns the primitive value of the specified object.
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 returnsNone.
Tests whether this JS value is a JS 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 theJsString::try_from() function from js-sysinstead.
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 thedocumentation about the str type which contains a few caveats about the encodings.
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 returnsNone.
Tests whether this JS value is null
Tests whether this JS value is undefined
Tests whether this JS value is null or undefined
Tests whether the type of this JS value is symbol
Tests whether typeof self == "object" && self !== null.
Tests whether this JS value is an instance of Array.
Tests whether the type of this JS value is function.
Tests whether the type of this JS value is bigint.
Tests whether the value is “truthy”.
Tests whether the value is “falsy”.
Applies the binary / JS operator on two JsValues, catching and returning any RangeError thrown.
Converts this type into a shared reference of the (usually inferred) input type.
Converts this type into a shared reference of the (usually inferred) input type.
Converts this type into a shared reference of the (usually inferred) input type.
The resulting type after dereferencing.
Dereferences the value.
The singular concrete type that all generic variants can be transmuted on
Converts to this type from the input type.
Converts to this type from the input type.
Converts to this type from the input type.
The Wasm ABI type that this converts from when coming back out from the ABI boundary.
Recover a Self from Self::Abi. Read more
The Wasm ABI type that this converts into when crossing the ABI boundary.
Convert self into Self::Abi so that it can be sent across the wasm ABI boundary.
The Wasm ABI type that this converts into when crossing the ABI boundary.
Convert self into Self::Abi so that it can be sent across the wasm ABI boundary.
Performs a dynamic instanceof check to see whether the JsValueprovided 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 has a 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
Test whether this JS value is an instance of the type T. Read more
Performs a dynamic check to see whether the JsValue provided is a value of this type. Read more
Same as RefFromWasmAbi::Abi
Same as RefFromWasmAbi::Anchor
Same as RefFromWasmAbi::ref_from_abi
Tests whether the argument is a “none” instance. If so it will be deserialized as None, and otherwise it will be passed toFromWasmAbi.
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
The type that this value resolves to.
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.
Recover a Self::Anchor from Self::Abi. Read more