Interface OptionMethods<T>

All the methods available on Option<T>.

interface OptionMethods<T> {
 and: (other: Option) => Option;
 andThen: (fn: (value: T) => Option) => Option;
 equals: (other: Option<T>) => boolean;
 expect: (msg: string) => T;
 filter: (fn: (value: T) => boolean) => Option<T>;
 flatten: () => Option<T>;
 isNone: () => boolean;
 isNoneOr: (fn: (value: T) => boolean) => boolean;
 isSome: () => boolean;
 isSomeAnd: (fn: (value: T) => boolean) => boolean;
 map: (fn: (value: T) => U) => Option;
 mapOr: (defaultValue: U, fn: (value: T) => U) => Option;
 mapOrElse: (defaultFn: () => U, mapFn: (value: T) => U) => Option;
 match: (cases: { none: () => U; some: (value: T) => U }) => U;
 okOr: <E>(defaultError: E) => Result<T, E>;
 okOrElse: <E>(fn: () => E) => Result<T, E>;
 or: (other: Option<T>) => Option<T>;
 orElse: (fn: () => Option<T>) => Option<T>;
 strictEquals: (other: Option<T>) => boolean;
 unwrap: () => T;
 unwrapOr: (defaultValue: T | U) => T | U;
 unwrapOrElse: (fn: () => T | U) => T | U;
 xor: (other: Option<T>) => Option<T>;
}

Type Parameters

T
The type of the wrapped value

Index

Equality Checks

equals

equals: (other: Option<T>) => boolean

Returns true if both options are Some and their inner values are equal using the JavaScript == operator, or if both options are None. If the inner values are both Options or Results, then the comparison will be recursive using equals on the inner values.

Type declaration

- (other: Option<T>): boolean
- Parameters
 - other: Option<T>
 The option to compare against.
 Returns boolean
 Whether the options are equal.

Example

const opt1 = Some(1);
const opt2 = Some(1);
const result = opt1.equals(opt2); // true

const opt3 = Some(Ok(1));
const opt4 = Some(Ok(1));
const result2 = opt3.equals(opt4); // true

const opt5 = Some(None);
const opt6 = Some(None);
const result3 = opt5.equals(opt6); // true

match

match: (cases: { none: () => U; some: (value: T) => U }) => U

Returns the result of calling cases.some() with the inner value if the option is Some, otherwise returns the result of calling cases.none().

Type declaration

- (cases: { none: () => U; some: (value: T) => U }): U
- Type Parameters
 - U
 The type of the result.
 Parameters
 - cases: { none: () => U; some: (value: T) => U }
 An object containing functions to handle both Some and None cases.
 Returns U
 The result of calling the appropriate function.

Example

const opt = Some(1);
const result = opt.match({
  some: (value) => value * 2,
  none: () => 0,
});

strictEquals

strictEquals: (other: Option<T>) => boolean

Returns true if both options are Some and their inner values are equal using the JavaScript === operator, or if both options are None. If the inner values are both Options or Results, then the comparison will be recursive using strictEquals on the inner values.

Type declaration

- (other: Option<T>): boolean
- Parameters
 - other: Option<T>
 Returns boolean
 Whether the options are strictly equal.

Example

const obj = {};
const opt1 = Some(obj);
const opt2 = Some(obj);
const result = opt1.strictEquals(opt2); // true

const opt3 = Some(None);
const opt4 = Some(None);
const result2 = opt3.strictEquals(opt4); // true

Query Methods

isNone

isNone: () => boolean

Returns true if the value is a None.

Type declaration

- (): boolean
- Returns boolean
  true if the value is a None, false otherwise.

Example

const opt = Some(1);
const result = opt.isNone(); // false

const none = None;
const result2 = none.isNone(); // true

isNoneOr

isNoneOr: (fn: (value: T) => boolean) => boolean

Returns true if the value is a None or the given function returns true.

Type declaration

- (fn: (value: T) => boolean): boolean
- Parameters
  - fn: (value: T) => boolean
    A function that takes the wrapped value and returns a boolean.
  Returns boolean
  true if the value is a None or the given function returns true, false otherwise.

Example

const opt = Some(1);
const result = opt.isNoneOr(value => value > 0); // true

const none = None;
const result2 = none.isNoneOr(value => value > 0); // true

isSome

isSome: () => boolean

Returns true if the value is a Some.

Type declaration

- (): boolean
- Returns boolean
  true if the value is a Some, false otherwise.

Example

const opt = Some(1);
const result = opt.isSome(); // true

const none = None;
const result2 = none.isSome(); // false

isSomeAnd

isSomeAnd: (fn: (value: T) => boolean) => boolean

Returns true if the value is a Some and the given function returns true.

Type declaration

- (fn: (value: T) => boolean): boolean
- Parameters
  - fn: (value: T) => boolean
    A function that takes the wrapped value and returns a boolean.
  Returns boolean
  true if the value is a Some and the given function returns true, false otherwise.

Example

const opt = Some(1);
const result = opt.isSomeAnd(value => value > 0); // true

const none = None;
const result2 = none.isSomeAnd(value => value > 0); // false

Transform Methods

and

and: (other: Option) => Option

Returns None if the source option is None, otherwise returns other.

Type declaration

- (other: Option): Option
- Type Parameters
 - U
 The type of the new wrapped value.
 Parameters
 - other: Option
 The option to return if this option is Some.
 Returns Option
 Either None or the provided option.

Example

const opt = Some(1);
const result = opt.and(Some(2)); // Some(2)

const none = None;
const result2 = none.and(Some(2)); // None

andThen

andThen: (fn: (value: T) => Option) => Option

Returns None if the source option is None, otherwise calls fn with the inner value and returns the result.

Type declaration

- (fn: (value: T) => Option): Option
- Type Parameters
 - U
 The type of the new wrapped value.
 Parameters
 - fn: (value: T) => Option
 A function that takes the wrapped value and returns a new option.
 Returns Option
 The result of fn or None.

Example

const opt = Some(1);
const result = opt.andThen(value => Some(value * 2)); // Some(2)

const none = None;
const result2 = none.andThen(value => Some(value * 2)); // None

filter

filter: (fn: (value: T) => boolean) => Option<T>

Returns None if the option is None, otherwise calls fn with the inner value and returns:

Some<T> with the original wrapped value if fn returns true
None if fn returns false

Type declaration

- (fn: (value: T) => boolean): Option<T>
- Parameters
 - fn: (value: T) => boolean
 A function that takes the wrapped value and returns a boolean.
 Returns Option<T>
 Either this option or None.

Example

const opt = Some(1);
const result = opt.filter(value => value > 0); // Some(1)

const opt2 = Some(1);
const result2 = opt2.filter(value => value < 0); // None

const none = None;
const result3 = none.filter(value => value > 0); // None

flatten

flatten: () => Option<T>

Converts from Option<Option<T>> to Option<T>. Only one level of nesting is removed.

Type declaration

- (): Option<T>
- Returns Option<T>
 The flattened option.

Example

const opt = Some(Some(1));
const result = opt.flatten(); // Some(1)

const opt2 = Some(Some(Some(1)));
const result2 = opt2.flatten(); // Some(Some(1))

const none = None;
const result3 = none.flatten(); // None

map

map: (fn: (value: T) => U) => Option

Returns an Option by mapping the inner value of the source option with fn.

Type declaration

- (fn: (value: T) => U): Option
- Type Parameters
 - U
 The type of the new wrapped value.
 Parameters
 - fn: (value: T) => U
 A function that takes the wrapped value and returns a new value.
 Returns Option
 A new option containing the transformed value.

Example

const opt = Some(1);
const result = opt.map(value => String(value)); // Some("1")

const none = None;
const result2 = none.map(value => String(value)); // None

mapOr

mapOr: (defaultValue: U, fn: (value: T) => U) => Option

Returns an option wrapping the provided defaultValue if the option is None, or calls fn with the inner value and returns a new option wrapping its return value.

Type declaration

- (defaultValue: U, fn: (value: T) => U): Option
- Type Parameters
 - U
 The type of the new wrapped value.
 Parameters
 - defaultValue: U
 The value to use if the option is None.
 - fn: (value: T) => U
 A function that takes the wrapped value and returns a new value.
 Returns Option

Example

const opt = Some(1);
const result = opt.mapOr("default", value => String(value)); // Some("1")

const none = None;
const result2 = none.mapOr("default", value => String(value)); // Some("default")

mapOrElse

mapOrElse: (defaultFn: () => U, mapFn: (value: T) => U) => Option

Returns an option wrapping the return value of defaultFn if the option is None, or calls mapFn with the inner value and returns a new option wrapping its return value. This function is useful for providing a default value that is expensive to compute or has side effects.

Type declaration

- (defaultFn: () => U, mapFn: (value: T) => U): Option
- Type Parameters
 - U
 The type of the new wrapped value.
 Parameters
 - defaultFn: () => U
 A function that returns the default value if the option is None.
 - mapFn: (value: T) => U
 A function that takes the wrapped value and returns a new value.
 Returns Option
 A new option containing either the default or transformed value.

Example

const opt = Some(1);
const result = opt.mapOrElse(() => "default", value => String(value)); // Some("1")

const none = None;
const result2 = none.mapOrElse(() => "default", value => String(value)); // Some("default")

okOr

okOr: <E>(defaultError: E) => Result<T, E>

Converts the Option<T> into a Result<T, E>, mapping Some(v) to Ok(v) and None to Err(defaultValue).

Type declaration

- <E>(defaultError: E): Result<T, E>
- Type Parameters
 - E
 The type of the error value.
 Parameters
 - defaultError: E
 The error value to use if the option is None.
 Returns Result<T, E>
 A result containing either the wrapped value or the error.

Example

const opt = Some(1);
const result = opt.okOr("default error"); // Ok(1)

const none = None;
const result2 = none.okOr("default error"); // Err("default error")

okOrElse

okOrElse: <E>(fn: () => E) => Result<T, E>

Converts the Option<T> into a Result<T, E>, mapping Some(v) to Ok(v) and None to Err(fn()).

Type declaration

- <E>(fn: () => E): Result<T, E>
- Type Parameters
 - E
 The type of the error value.
 Parameters
 - fn: () => E
 A function that returns the error value if the option is None.
 Returns Result<T, E>
 A result containing either the wrapped value or the error.

Example

const opt = Some(1);
const result = opt.okOrElse(() => "default error"); // Ok(1)

const none = None;
const result2 = none.okOrElse(() => "default error"); // Err("default error")

or

or: (other: Option<T>) => Option<T>

Returns the source option if it is Some, otherwise returns other.

Type declaration

- (other: Option<T>): Option<T>
- Parameters
 - other: Option<T>
 The option to return if this option is None.
 Returns Option<T>
 Either this option or the provided option.

Example

const opt = Some(1);
const result = opt.or(Some(2)); // Some(1)

const none = None;
const result2 = none.or(Some(2)); // Some(2)

orElse

orElse: (fn: () => Option<T>) => Option<T>

Returns the source option if it is Some, otherwise calls fn and returns the result. This function is useful for providing a default value that is expensive to compute or has side effects.

Type declaration

- (fn: () => Option<T>): Option<T>
- Parameters
 - fn: () => Option<T>
 A function that returns a new option.
 Returns Option<T>
 Either this option or the result of fn.

Example

const opt = Some(1);
const result = opt.orElse(() => Some(2)); // Some(1)

const none = None;
const result2 = none.orElse(() => Some(2)); // Some(2)

xor

xor: (other: Option<T>) => Option<T>

Returns the source option or other if exactly one of them is Some, otherwise returns None.

Type declaration

- (other: Option<T>): Option<T>
- Parameters
 - other: Option<T>
 The option to compare against.
 Returns Option<T>
 Either this option, the other option, or None.

Example

const opt1 = Some(1);
const opt2 = Some(2);
const result = opt1.xor(opt2); // None

const none = None;
const result2 = none.xor(Some(2)); // Some(2)

Unwrap Methods

expect

expect: (msg: string) => T

Returns the wrapped value. If the option is None, this will throw an error with the provided message.

Type declaration

- (msg: string): T
- Parameters
  - msg: string
    The message to throw if the option is None.
  Returns T
  The wrapped value.

Example

const opt = Some(1);
const result = opt.expect("Expected a value"); // 1

const none = None;
const result2 = none.expect("Expected a value"); // throws Error

unwrap

unwrap: () => T

Returns the wrapped value. If the option is None, this will throw an error.

Type declaration

- (): T
- Returns T
  The wrapped value.

Example

const opt = Some(1);
const result = opt.unwrap(); // 1

const none = None;
const result2 = none.unwrap(); // throws Error

unwrapOr

unwrapOr: (defaultValue: T | U) => T | U

Returns the wrapped value. If the option is None, this will return the provided default value.

Type declaration

- (defaultValue: T | U): T | U
- Type Parameters
 - U
 Parameters
 - defaultValue: T | U
 The value to return if the option is None.
 Returns T | U
 The wrapped value.

Example

const opt = Some(1);
const result = opt.unwrapOr(0); // 1

const none = None;
const result2 = none.unwrapOr(0); // 0

unwrapOrElse

unwrapOrElse: (fn: () => T | U) => T | U

Returns the wrapped value. If the option is None, this will call the provided function and return its result. This function is useful for providing a default value that is expensive to compute or has side effects.

Type declaration

- (fn: () => T | U): T | U
- Type Parameters
 - U
 Parameters
 - fn: () => T | U
 A function that returns the default value if the option is None.
 Returns T | U
 The wrapped value.

Example

const opt = Some(1);
const result = opt.unwrapOrElse(() => 0); // 1

const none = None;
const result2 = none.unwrapOrElse(() => 0); // 0

Interface OptionMethods<T>

Type Parameters

Index

Equality Checks

Query Methods

Transform Methods

Unwrap Methods

Equality Checks

equals

Type declaration

Parameters

Returns boolean

Example

match

Type declaration

Type Parameters

Parameters

Returns U

Example

strictEquals

Type declaration

Parameters

Returns boolean

Example

Query Methods

isNone

Type declaration

Returns boolean

Example

isNoneOr

Type declaration

Parameters

Returns boolean

Example

isSome

Type declaration

Returns boolean

Example

isSomeAnd

Type declaration

Parameters

Returns boolean

Example

Transform Methods

and

Type declaration

Type Parameters

Parameters

Returns Option<U>

Example

andThen

Type declaration

Type Parameters

Parameters

Returns Option<U>

Example

filter

Type declaration

Parameters

Returns Option<T>

Example

flatten

Type declaration

Returns Option<T>

Example

map

Type declaration

Type Parameters

Parameters

Returns Option<U>

Example

mapOr

Type declaration

Type Parameters

Parameters

Returns Option<U>

Example

mapOrElse

Type declaration

Type Parameters