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Class: Optional<T>

A container object that wraps possibly undefined values.

Type parameters

Name
T

Table of contents

Constructors

Methods

Constructors

constructor

• Private new Optional<T>(value?)

Type parameters

Name
T

Parameters

Name Type
value? null | T

Defined in

index.ts:11

Methods

filter

▸ filter(predicate): Optional<T>

Checks the value in the optional for a certain condition. Will be skipped if the optional is empty.

Parameters

Name Type Description
predicate (value: T) => boolean The predicate that checks if the optional value should be passed

Returns

Optional<T>

The optional itself if the predicate is true. Returns an empty optional if the predicate is false or the optional is empty.

flatMap

▸ flatMap<U>(mapper): Optional<U>

Maps the optional value to another optional. Will be skipped if the optional is empty.

Type parameters

Name
U

Parameters

Name Type Description
mapper (value: T) => Optional<U> The mapper function that transforms the value into another optional

Returns

Optional<U>

An optional that is produced by the mapper function or an empty optional if no value is present.

get

▸ get(): T

Returns the value that is wrapped in the optional.

throws Error if the optional is empty

Returns

T

The wrapped value

guard

▸ guard(predicate, exceptionSupplier): Optional<T>

Checks for the given condition and throws an exception if the condition fails.

throws Error if the condition isn't met.

Parameters

Name Type Description
predicate (value: T) => boolean The condition that needs to be fulfilled to go on
exceptionSupplier () => Error A supplier that generates an {@link Error} if the condition fails

Returns

Optional<T>

The current optional if the condition is fulfilled

ifPresent

▸ ifPresent(consumer): void

Executes a consumer callback if the optional contains a value.

Parameters

Name Type Description
consumer (value: T) => void The callback to execute

Returns

void

ifPresentOrElse

▸ ifPresentOrElse(presentAction, emptyAction): void

Executes one of the given callbacks.

Parameters

Name Type Description
presentAction (value: T) => void The callback to execute if the optional has a value
emptyAction () => void The callback to execute if the optional is empty

Returns

void

isEmpty

▸ isEmpty(): boolean

Defines if the optional is empty. Opposite of isPresent

Returns

boolean

isPresent

▸ isPresent(): boolean

Checks if the optional contains a value. Opposite of isPresent

Returns

boolean

map

▸ map<U>(mapper): Optional<U>

Maps the optional value to something else. Will be skipped if the optional is empty.

Type parameters

Name
U

Parameters

Name Type Description
mapper (value: T) => undefined | null | U The mapper function that transforms the optional value

Returns

Optional<U>

An optional that contains the mapped value or is empty if the map returned a nullish value

or

▸ or<U>(optionalSupplier): Optional<T | U>

If the current optional is empty then another optional is generated and returned.

Type parameters

Name
U

Parameters

Name Type Description
optionalSupplier () => Optional<U> A supplier callback that generates an alternative optional

Returns

Optional<T | U>

The current optional or the generated optional if the current one is empty

orElse

▸ orElse<U>(other): T | U

Returns the value of the optional or the given value if the optional is empty.

Type parameters

Name
U

Parameters

Name Type Description
other U The value to return if the optional is empty

Returns

T | U

The value from the optional or the alternative value

orElseGet

▸ orElseGet<U>(supplier): T | U

Returns the value of the optional or the value of the given supplier if the optional is empty.

Type parameters

Name
U

Parameters

Name Type Description
supplier () => U The supplier that generates an alternative value if the optional is empty

Returns

T | U

The value from the optional or the alternative value

orElseThrow

▸ orElseThrow(exceptionSupplier): T

Returns the value of the optional or throws an error if the optional is empty.

Parameters

Name Type Description
exceptionSupplier () => Error The supplier that generates an error if the optional is empty

Returns

T

The value from the optional

orThrow

▸ orThrow(exceptionSupplier): Optional<T>

Throws an exception if the current value of the optional is empty.

throws Error if the optional is empty

Parameters

Name Type Description
exceptionSupplier () => Error The supplier that generates an error if the optional is empty

Returns

Optional<T>

The current optional if the value is not empty

wrapInArray

▸ wrapInArray(): [T] | []

Returns the value of the optional wrapped in an array. If the optional is empty then the array will be empty too.

Type parameters

Name
T

Returns

[T] | []

An array that is either empty or contains the value

empty

▸ Static empty<T>(): Optional<T>

Creates an empty optional.

Type parameters

Name
T

Returns

Optional<T>

of

▸ Static of<T>(value): Optional<T>

Creates an Optional from a non-null value.

Type parameters

Name
T

Parameters

Name Type Description
value T The value to wrap

Returns

Optional<T>

the created optional with the given value

ofNullable

▸ Static ofNullable<T>(value): Optional<T>

Creates an Optional from a value that might be null.

Type parameters

Name
T

Parameters

Name Type Description
value undefined | null | T The value to wrap

Returns

Optional<T>

the created optional with the given value