Class IErr<ErrType>

Result Err instance.

Note: this class should not be used directly, use Err function instead

Since

v1.0.0

Type Parameters

ErrType
error type

Implements

IResultBuild<false, never, ErrType>

Index

Constructors

constructor

new IErr<ErrType>(error: ErrType | IJsonErr<ErrType>): IErr<ErrType>
Type Parameters
- ErrType
Parameters
- error: ErrType | IJsonErr<ErrType>
Returns IErr<ErrType>
- Defined in src/result/ErrInstance.mts:15

Accessors

isErr

get isErr(): true
Check that result is an error

Returns true
true if result is an error
Example
```
Ok<number>(2).isErr // false
Err<Error>(new Error('broken')).isErr // true
```
Implementation of IResultBuild.isErr
- Defined in src/result/ErrInstance.mts:35

isOk

get isOk(): false
Check that result is not an error

Returns false
true if result is not an error
Example
```
Ok<number>(2).isOk // true
Err<Error>(new Error('broken')).isOk // false
```
Implementation of IResultBuild.isOk
- Defined in src/result/ErrInstance.mts:19

Methods

and

and<CompareResult extends IResult>(_value: CompareResult): this
Method to combine two results, if the first result is true return the second result, otherwise return the first result
Type Parameters
- CompareResult extends IResult
Parameters
- _value: CompareResult
Returns this
- Result based on the self value and the value parameter
Example
```
Err<Error>(new Error('broken')).and(Ok<number>(3)) // Err<Error>(new Error('broken'))
Ok<number>(2).and(Err<number>(new Error('broken'))) // Err<Error>(new Error('broken'))
Ok<number>(2).and(Ok<number>(3)) // Ok<number>(3)
```
Implementation of IResultBuild.and
- Defined in src/result/ErrInstance.mts:92

andThen

andThen<OutResult extends IResult<unknown, unknown>>(
_callbackFunc: (val: never) => OutResult,
): this
Method to combine two results, if the first result is true use the value to build a new result, otherwise return the error
Type Parameters
- OutResult extends IResult<unknown, unknown>
Parameters
- _callbackFunc: (val: never) => OutResult
Returns this
- Result based on the self value and the value parameter
Example
```
Ok<number>(2).andThen<IResult<number>>((val) => Ok(val + 1)) // Ok<number>(3)
Err<'broken'>('broken').andThen<IResult<number>>((val) => Ok(val + 1)) // Err<'broken'>('broken')
```
Implementation of IResultBuild.andThen
- Defined in src/result/ErrInstance.mts:100

andThenPromise

andThenPromise<OutResult extends IResult<unknown, unknown>>(
_callbackFunc: (val: never) => Promise<OutResult>,
): this
Method to combine two results, if the first result is true use the value to build a new result from Promise, otherwise return the error
Type Parameters
- OutResult extends IResult<unknown, unknown>
Parameters
- _callbackFunc: (val: never) => Promise<OutResult>
Returns this
- Result based on the self value and the value parameter
Example
```
await Ok<number>(2).andThen<IResult<number>>((val) => Promise.resolve(Ok(val + 1))) // Ok<number>(3)
await Err<'broken'>('broken').andThen<IResult<number>>((val) => Promise.resolve(Ok(val + 1))) // Err<'broken'>('broken')
```
Implementation of IResultBuild.andThenPromise
- Defined in src/result/ErrInstance.mts:104

clone

clone(): IErr<ErrType>
Method to clone an result

Returns IErr<ErrType>
- cloned result instance
Example
```
const x = Ok(2);
const y = x.clone(); // Ok(2)
```
Implementation of IResultBuild.clone
- Defined in src/result/ErrInstance.mts:96

eq

eq(other: IResult): boolean
Method to compare two results
Parameters
- other: IResult
  other result to compare
Returns boolean
true if results are equal
Example
```
Ok<number>(2).eq(Ok<number>(2)) // true
Ok<number>(2).eq(Ok<number>(3)) // false
Err<number>(2).eq(Err<number>(2)) // true
```
Implementation of IResultBuild.eq
- Defined in src/result/ErrInstance.mts:76

err

err(): ErrType
Try to get the error, otherwise return undefined

Returns ErrType
error or undefined
Example
```
Ok<number>(2).err() // undefined
Err<Error>(new Error('broken')).err() // Error('broken')
```
Implementation of IResultBuild.err
- Defined in src/result/ErrInstance.mts:39

inspect

inspect(_fn: (value: never) => void): this
Inspect the result value if Ok
Parameters
- _fn: (value: never) => void
Returns this
this result instance
Example
```
Ok<number>(2).inspect((value) => console.log('Value:', value)).unwrap() // logs 'Value: 2' and returns 2
```
Since
v1.0.8
Implementation of IResultBuild.inspect
- Defined in src/result/ErrInstance.mts:116

inspectErr

inspectErr(fn: (value: ErrType) => void): this
Inspect the result value if Err
Parameters
- fn: (value: ErrType) => void
  function to inspect the error
Returns this
this result instance
Example
```
Err<Error>(new Error('broken')).inspectErr((err) => console.error('Error:', err)).unwrap() // logs 'Error: Error('broken')' and throws
```
Since
v1.0.8
Implementation of IResultBuild.inspectErr
- Defined in src/result/ErrInstance.mts:125

isErrAnd

isErrAnd(callbackFunc: (value: ErrType) => boolean): boolean
Returns true if the result is Err and callback function returns true for the value inside of Err.
Parameters
- callbackFunc: (value: ErrType) => boolean
Returns boolean
true if the result is Err and the callback function returns true for the value inside of Err
Example
```
Err<Error>(new Error('broken')).isErrAnd((err) => err.message === 'broken') // true
Err<Error>(new Error('broken')).isErrAnd((err) => err.message === 'not broken') // false
Ok<number>(2).isErrAnd((err) => err.message === 'broken') // false
```
Since
v1.0.8
Implementation of IResultBuild.isErrAnd
- Defined in src/result/ErrInstance.mts:27

isOkAnd

isOkAnd(_callbackFunc: (value: never) => boolean): false
Returns true if the result is Ok and callback function returns true for the value inside of Ok.
Parameters
- _callbackFunc: (value: never) => boolean
Returns false
true if the result is Ok and the callback function returns true for the value inside of Ok
Example
```
Ok<number>(2).isOkAnd((value) => value === 2) // true
Ok<number>(2).isOkAnd((value) => value === 3) // false
Err<Error>(new Error('broken')).isOkAnd((value) => value === 2) // false
```
Since
v1.0.8
Implementation of IResultBuild.isOkAnd
- Defined in src/result/ErrInstance.mts:23

iter

iter(): IterableIterator<INone>
Iterate over the result value

Returns IterableIterator<INone>
iterable iterator of the result value
Example
```
Ok<number>(2).iter().next().value; // Ok<number>(2)
Err<Error>(new Error('broken')).iter().next().done; // true (no values to iterate)
```
Since
v1.0.9
Implementation of IResultBuild.iter
- Defined in src/result/ErrInstance.mts:130

map

map<NewOkType>(_callbackFunc: (val: never) => NewOkType): this
Map the result value to a new value if Ok
Type Parameters
- NewOkType
Parameters
- _callbackFunc: (val: never) => NewOkType
Returns this
Example
```
Ok<string, Error>('hello').map((v)=> Buffer.from(v)) // Ok<Buffer, Error>
Err<Error, string>(new Error('broken')).map((v)=> Buffer.from(v)) // Err<Error, Buffer>
```
Since
v1.0.4
Implementation of IResultBuild.map
- Defined in src/result/ErrInstance.mts:108

mapErr

mapErr<NewErrType>(fn: (value: ErrType) => NewErrType): IErr<NewErrType>

Map the error value to a new value if Err

Type Parameters

NewErrType

Parameters

fn: (value: ErrType) => NewErrType
function to map the error value

Returns IErr<NewErrType>

new error result instance with mapped error

Example

const mapAsTypeErr = (err: Error): TypeError => new TypeError(`Mapped: ${err.message}`);
Err<Error>(new Error('broken')).mapErr(mapAsTypeErr) // Err<TypeError>(new TypeError('Mapped: broken'))
Ok<number>(2).mapErr(mapAsTypeErr); // Ok<number>(2)
// error mapping and logging example
const logErr = (err: Error) => console.error('Error:', err);
Err<Error>(new Error('broken')).mapErr(mapAsTypeErr).inspectErr(logErr);

Since

v1.0.4

ok

ok(): undefined
Try to get value, otherwise return undefined

Returns undefined
value or undefined
Example
```
Ok<number>(2).ok() // 2
Err<Error>(new Error('broken')).ok() // undefined
```
Implementation of IResultBuild.ok
- Defined in src/result/ErrInstance.mts:31

or

or<CompareResult extends IResult>(value: CompareResult): CompareResult
Method to combine two results, if the first result is false return the second result, otherwise return the first result
Type Parameters
- CompareResult extends IResult
Parameters
- value: CompareResult
  compare value
Returns CompareResult
- Result based on the self value and the value parameter
Example
```
Err<Error>(new Error('broken')).or(Ok<number>(3)) // Ok<number>(3)
Ok<number>(2).or(Err<Error>(new Error('broken'))) // Ok<number>(2)
Ok<number>(2).or(Ok<number>(3)) // Ok<number>(2)
```
Implementation of IResultBuild.or
- Defined in src/result/ErrInstance.mts:80

orElse

orElse<OutResult extends IResult<unknown, unknown>>(
callbackFunc: (value: ErrType) => OutResult,
): OutResult
Method to combine two results, if the first result is false use the error to build a new result, otherwise return the first result
Type Parameters
- OutResult extends IResult<unknown, unknown>
Parameters
- callbackFunc: (value: ErrType) => OutResult
  callback to build a new result
Returns OutResult
- Result based on the self value and the value parameter
Example
```
Ok<number>(2).orElse<IResult<number>>((errValue) => Ok(errValue * 2)) // Ok<number>(2)
Err<number>(2).orElse<IResult<number>>((errValue) => Ok(errValue * 2)) // Ok<number>(4)
```
Implementation of IResultBuild.orElse
- Defined in src/result/ErrInstance.mts:84

orElsePromise

orElsePromise<OutResult extends IResult<unknown, unknown>>(
callbackFunc: (value: ErrType) => Promise<OutResult>,
): Promise<OutResult>
Method to combine two results, if the first result is false use the error to build a new result from Promise, otherwise return the first result
Type Parameters
- OutResult extends IResult<unknown, unknown>
Parameters
- callbackFunc: (value: ErrType) => Promise<OutResult>
  callback to build a new result
Returns Promise<OutResult>
- Result based on the self value and the value parameter
Example
```
await Ok<number>(2).orElsePromise<IResult<number>>((errValue) => Promise.resolve(Ok(errValue * 2))) // Ok<number>(2)
await Err<number>(2).orElsePromise<IResult<number>>((errValue) => Promise.resolve(Ok(errValue * 2))) // Ok<number>(4)
```
Implementation of IResultBuild.orElsePromise
- Defined in src/result/ErrInstance.mts:88

toJSON

toJSON(): IJsonErr<ErrType>
Convert result to JSON {$class: 'Result::Ok', value: OkType} or {$class: 'Result::Err', value: ErrType}

Returns IJsonErr<ErrType>
JSON representation of the result
Example
```
Ok<number>(2).toJSON() // {$class: 'Result::Ok', value: 2}
Err<number>(2).toJSON() // {$class: 'Result::Err', value: 2}
```
Implementation of IResultBuild.toJSON
- Defined in src/result/ErrInstance.mts:142

toOption

toOption(): INone<never>
Convert result to option and discard the error type

Returns INone<never>
option
Example
```
Ok<number>(2).toOption() // Some<number>(2)
Err<number>(2).toOption() // None<never>()
```
Implementation of IResultBuild.toOption
- Defined in src/result/ErrInstance.mts:43

toString

toString(): `Err(${string})`
Convert result to string

Returns `Err(${string})`
string representation of the result
Example
```
Ok<number>(2).toString() // 'Ok(2)'
Err<number>(2).toString() // 'Err(2)'
```
Implementation of IResultBuild.toString
- Defined in src/result/ErrInstance.mts:138

unwrap

unwrap(): never
Method to unwrap the value or throw an error.

Note: Error argument/callback was removed in favor of the .errMap((e) => new Error(e.message)).unwrap() method.

Returns never
Example
```
Ok<number>(2).unwrap() // 2
Err<Error>(new Error('broken')).unwrap() // throws Error('broken')
```
Implementation of IResultBuild.unwrap
- Defined in src/result/ErrInstance.mts:47

unwrapOr

unwrapOr<DefaultType>(defaultValue: DefaultType): DefaultType
Method to unwrap the value or if error return the default value
Type Parameters
- DefaultType
Parameters
- defaultValue: DefaultType
  default value to return if error
Returns DefaultType
Example
```
Ok<number>(2).unwrapOr(0) // 2
Err<number>(new Error('broken')).unwrapOr(0) // 0
```
Implementation of IResultBuild.unwrapOr
- Defined in src/result/ErrInstance.mts:64

unwrapOrElse

unwrapOrElse<DefaultType>(callbackFunc: () => DefaultType): DefaultType
Method to unwrap the value or if error return default value from function
Type Parameters
- DefaultType
Parameters
- callbackFunc: () => DefaultType
  function to return default value
Returns DefaultType
Example
```
Ok<number>(2).unwrapOrElse(() => 0) // 2
Err<number>(new Error('broken')).unwrapOrElse(() => 0) // 0
```
Implementation of IResultBuild.unwrapOrElse
- Defined in src/result/ErrInstance.mts:68

unwrapOrValueOf

unwrapOrValueOf<ValueType>(
BaseConstructor: ConstructorWithValueOf<ValueType>,
): ValueType
Method to unwrap the value or if error return default value from constructors valueOf
Type Parameters
- ValueType
Parameters
- BaseConstructor: ConstructorWithValueOf<ValueType>
  constructor to return default value from valueOf
Returns ValueType
Example
```
Ok<number>(2).unwrapOrValueOf(Number) // 2
Err<Error>(new Error('broken')).unwrapOrValueOf(Number) // 0 (Number.valueOf())
```
Implementation of IResultBuild.unwrapOrValueOf
- Defined in src/result/ErrInstance.mts:72

Class IErr<ErrType>

Since

Type Parameters

Implements

Index

Constructors

Accessors

Methods

Constructors

constructor

Type Parameters

Parameters

Returns IErr<ErrType>

Accessors

isErr

Returns true

Example

isOk

Returns false

Example

Methods

and

Type Parameters

Parameters

Returns this

Example

andThen

Type Parameters

Parameters

Returns this

Example

andThenPromise

Type Parameters

Parameters

Returns this

Example

clone

Returns IErr<ErrType>

Example

eq

Parameters

Returns boolean

Example

err

Returns ErrType

Example

inspect

Parameters

Returns this

Example

Since

inspectErr

Parameters

Returns this

Example

Since

isErrAnd

Parameters

Returns boolean

Example

Since

isOkAnd

Parameters

Returns false

Example

Since

iter

Returns IterableIterator<INone>

Example

Since

map

Type Parameters

Parameters

Returns this

Example

Since

mapErr

Type Parameters

Parameters

Returns IErr<NewErrType>