Class Optional<T>

Wrapper for an optional value that might or might not be present

Type Parameters

Index

Methods

empty filter flatMap ifEmpty ifPresent isEmpty isPresent map of orCrash orElse orFail orGet

Methods

`Static`empty

empty<T>(): Optional<Exclude<T, null>>
Create an empty Optional instance
Type Parameters
- T
Returns Optional<Exclude<T, null>>
An empty Optional

filter

filter(filter: (value: T) => unknown): Optional<T>
Filter the value (if present)
Parameters
- filter: (value: T) => unknown
  A predicate that returns a truthy value (if the Optional's value should be preserved) or a falsy value (if the Optional's value should be discarded)
Returns Optional<T>
The current Optional (if it is not empty and if the filter returns a truthy value) or an empty Optional (if if the current Optional is empty or if the filter returns a falsy value)

flatMap

flatMap<R>(map: (value: T) => Optional<R>): Optional<R>
Map the value (if present) to another Optional and unwrap it
Type Parameters
- R
Parameters
- map: (value: T) => Optional<R>
  A function that maps the current Optional's value to another Optional
Returns Optional<R>
The Optional returned by the map function (if the current Optional is present) or an empty optional (if the current Optional is empty)

ifEmpty

ifEmpty(action: () => void): this
Perform an action if the Optional does not contain a value
Parameters
- action: () => void
  The action to perform
Returns this
The current Optional

ifPresent

ifPresent(action: (value: T) => void): this
Perform an action if the Optional contains a value
Parameters
- action: (value: T) => void
  The action to perform
Returns this
The current Optional

isEmpty

isEmpty(): boolean
Check if the Optional is empty

Returns boolean

isPresent

isPresent(): this is Optional<T> & { get: () => T }
Check if the Optional contains a value

Returns this is Optional<T> & { get: () => T }

map

map<R>(map: (value: T) => R): Optional<Exclude<R, null>>
Map the value (if present)
Type Parameters
- R
Parameters
- map: (value: T) => R
Returns Optional<Exclude<R, null>>

`Static`of

of<T>(value: T): Optional<Exclude<T, null>>
Create an optional
Type Parameters
- T
Parameters
- value: T
Returns Optional<Exclude<T, null>>

orCrash

orCrash(message: string): T
Get the value (if present) or fail with a an internal error
Parameters
- message: string
Returns T

orElse

orElse<U>(fallbackValue: U): T | U
Get the value (if present) or return the specified default value otherwise
Type Parameters
- U
Parameters
- fallbackValue: U
Returns T | U

orFail

orFail(message: string): T
Get the value (if present) or fail with a user-friendly error message
Parameters
- message: string
Returns T

orGet

orGet<U>(get: () => U): T | U
Get the value (if present) or call the specified function and return its return value otherwise
Type Parameters
- U
Parameters
- get: () => U
Returns T | U

Class Optional<T>

Type Parameters

Index

Methods

Methods

Staticempty

Type Parameters

Returns Optional<Exclude<T, null>>

filter

Parameters

Returns Optional<T>

flatMap

Type Parameters

Parameters

Returns Optional<R>

ifEmpty

Parameters

Returns this

ifPresent

Parameters

Returns this

isEmpty

Returns boolean

isPresent

Returns this is Optional<T> & { get: () => T }

map

Type Parameters

Parameters

Returns Optional<Exclude<R, null>>

Staticof

Type Parameters

Parameters

Returns Optional<Exclude<T, null>>

orCrash

Parameters

Returns T

orElse

Type Parameters

Parameters

Returns T | U

orFail

Parameters

Returns T

orGet

Type Parameters

Parameters

Returns T | U

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`Static`empty

`Static`of