LazyPromise Class

A lazy evaluated promise. The execute function is delayed until the promise is used, e.g. await, then, catch ... The execute function is only called once. All calls are then proxied to the promise returned by the execute method.

This API is provided for existing users, but is not recommended for new users.

To use, import via @fluidframework/core-utils/legacy.

For more information about our API support guarantees, see here.

Signature

export declare class LazyPromise<T> implements Promise<T>

Implements: Promise<T>

Type Parameters

Parameter	Description
T

Constructors

Constructor	Alerts	Description
(constructor)(execute)	Beta	Constructs a new instance of the LazyPromise class

Properties

Property	Alerts	Modifiers	Type	Description
[Symbol.toStringTag]	Beta	readonly	string

Methods

Method	Alerts	Return Type	Description
catch(onrejected)	Beta	Promise<T | TResult>
finally(onfinally)	Beta	Promise<T>
then(onfulfilled, onrejected)	Beta	Promise<TResult1 | TResult2>

Constructor Details

(constructor)

Constructs a new instance of the LazyPromise class

This API is provided for existing users, but is not recommended for new users.

For more information about our API support guarantees, see here.

Signature

constructor(execute: () => Promise<T>);

Parameters

Parameter	Type	Description
execute	() => Promise<T>

Property Details

[Symbol.toStringTag]

This API is provided for existing users, but is not recommended for new users.

For more information about our API support guarantees, see here.

Signature

get [Symbol.toStringTag](): string;

Type: string

Method Details

catch

This API is provided for existing users, but is not recommended for new users.

For more information about our API support guarantees, see here.

Signature

catch<TResult = never>(onrejected?: ((reason: any) => TResult | PromiseLike<TResult>) | null | undefined): Promise<T | TResult>;

Type Parameters

Parameter	Default	Description
TResult	never

Parameters

Parameter	Modifiers	Type	Description
onrejected	optional	((reason: any) => TResult | PromiseLike<TResult>) | null | undefined

Returns

Return type: Promise<T | TResult>

finally

This API is provided for existing users, but is not recommended for new users.

For more information about our API support guarantees, see here.

Signature

finally(onfinally?: (() => void) | null | undefined): Promise<T>;

Parameters

Parameter	Modifiers	Type	Description
onfinally	optional	(() => void) | null | undefined

Returns

Return type: Promise<T>

then

This API is provided for existing users, but is not recommended for new users.

For more information about our API support guarantees, see here.

Signature

then<TResult1 = T, TResult2 = never>(onfulfilled?: ((value: T) => TResult1 | PromiseLike<TResult1>) | null | undefined, onrejected?: ((reason: any) => TResult2 | PromiseLike<TResult2>) | null | undefined): Promise<TResult1 | TResult2>;

Type Parameters

Parameter	Default	Description
TResult1	T
TResult2	never

Parameters

Parameter	Modifiers	Type	Description
onfulfilled	optional	((value: T) => TResult1 | PromiseLike<TResult1>) | null | undefined
onrejected	optional	((reason: any) => TResult2 | PromiseLike<TResult2>) | null | undefined

Returns

Return type: Promise<TResult1 | TResult2>