toResult

Converts a PromiseLike to a Promise<Result>

Usage

Converts a PromiseLike to a Promise<Result>.

import { 
function toResult<T>(promise: PromiseLike<T>): Promise<Result<T>>
Converts a PromiseLike to a Promise<Result>.
Note: If the given promise throws a non-Error value, it will be
rethrown.
@see ― https://radashi.js.org/reference/async/toResult
@example 
import { toResult, Result } from 'radashi'

const good = async (): Promise<number> => 1
const bad = async (): Promise<number> => { throw new Error('bad') }

const goodResult = await toResult(good())
// => [undefined, 1]

const badResult = await toResult(bad())
// => [Error('bad'), undefined]
@version ― 12.4.0
toResult, 
type Result<TResult, TError extends Error = Error> = Ok<TResult> | Err<TError>
A result tuple.
First index is the error, second index is the result.
@example 
type MyResult = Result<string>
//   ^? Ok<string> | Err<Error>

type MyResult2 = Result<string, TypeError>
//   ^? Ok<string> | Err<TypeError>
Result } from 'radashi'

const 
const good: () => Promise<number>
good = async (): 
interface Promise<T>
Represents the completion of an asynchronous operation
Promise<number> => 1
const 
const bad: () => Promise<number>
bad = async (): 
interface Promise<T>
Represents the completion of an asynchronous operation
Promise<number> => {
  throw new 
var Error: ErrorConstructor
new (message?: string, options?: ErrorOptions) => Error (+1 overload)
Error('bad')
}

const 
const goodResult: Result<number>
goodResult = await 
toResult<number>(promise: PromiseLike<number>): Promise<Result<number>>
Converts a PromiseLike to a Promise<Result>.
Note: If the given promise throws a non-Error value, it will be
rethrown.
@see ― https://radashi.js.org/reference/async/toResult
@example 
import { toResult, Result } from 'radashi'

const good = async (): Promise<number> => 1
const bad = async (): Promise<number> => { throw new Error('bad') }

const goodResult = await toResult(good())
// => [undefined, 1]

const badResult = await toResult(bad())
// => [Error('bad'), undefined]
@version ― 12.4.0
toResult(
const good: () => Promise<number>
good())
// => [undefined, 1]

const 
const badResult: Result<number>
badResult = await 
toResult<number>(promise: PromiseLike<number>): Promise<Result<number>>
Converts a PromiseLike to a Promise<Result>.
Note: If the given promise throws a non-Error value, it will be
rethrown.
@see ― https://radashi.js.org/reference/async/toResult
@example 
import { toResult, Result } from 'radashi'

const good = async (): Promise<number> => 1
const bad = async (): Promise<number> => { throw new Error('bad') }

const goodResult = await toResult(good())
// => [undefined, 1]

const badResult = await toResult(bad())
// => [Error('bad'), undefined]
@version ― 12.4.0
toResult(
const bad: () => Promise<number>
bad())
// => [Error('bad'), undefined]

Throwing non-Error values

If the given promise throws a non-Error value, it will be rethrown. This ensures the Result always contains an Error value or undefined.

import { 
function toResult<T>(promise: PromiseLike<T>): Promise<Result<T>>
Converts a PromiseLike to a Promise<Result>.
Note: If the given promise throws a non-Error value, it will be
rethrown.
@see ― https://radashi.js.org/reference/async/toResult
@example 
import { toResult, Result } from 'radashi'

const good = async (): Promise<number> => 1
const bad = async (): Promise<number> => { throw new Error('bad') }

const goodResult = await toResult(good())
// => [undefined, 1]

const badResult = await toResult(bad())
// => [Error('bad'), undefined]
@version ― 12.4.0
toResult } from 'radashi'

// This won't catch the rejected promise, because it was
// rejected with a string, not an Error.
const 
const res: Result<never>
res = await 
toResult<never>(promise: PromiseLike<never>): Promise<Result<never>>
Converts a PromiseLike to a Promise<Result>.
Note: If the given promise throws a non-Error value, it will be
rethrown.
@see ― https://radashi.js.org/reference/async/toResult
@example 
import { toResult, Result } from 'radashi'

const good = async (): Promise<number> => 1
const bad = async (): Promise<number> => { throw new Error('bad') }

const goodResult = await toResult(good())
// => [undefined, 1]

const badResult = await toResult(bad())
// => [Error('bad'), undefined]
@version ― 12.4.0
toResult(
var Promise: PromiseConstructor
Represents the completion of an asynchronous operation
Promise.
PromiseConstructor.reject<never>(reason?: any): Promise<never>
Creates a new rejected promise for the provided reason.
@param ― reason The reason the promise was rejected.
@returns ― A new rejected Promise.
reject('test error'))

Synchronous errors

This function won’t catch synchronous errors. Only rejected promises are converted to an Err.

import { 
function toResult<T>(promise: PromiseLike<T>): Promise<Result<T>>
Converts a PromiseLike to a Promise<Result>.
Note: If the given promise throws a non-Error value, it will be
rethrown.
@see ― https://radashi.js.org/reference/async/toResult
@example 
import { toResult, Result } from 'radashi'

const good = async (): Promise<number> => 1
const bad = async (): Promise<number> => { throw new Error('bad') }

const goodResult = await toResult(good())
// => [undefined, 1]

const badResult = await toResult(bad())
// => [Error('bad'), undefined]
@version ― 12.4.0
toResult } from 'radashi'

function 
function bad(): Promise<unknown>
bad() {
  if (
var Math: Math
An intrinsic object that provides basic mathematics functionality and constants.
Math.
Math.random(): number
Returns a pseudorandom number between 0 and 1.
random() > 0.5) {
    // ⚠️ This error won't be caught by `toResult`. To fix this, add
    // the `async` keyword to the containing function.
    throw new 
var Error: ErrorConstructor
new (message?: string, options?: ErrorOptions) => Error (+1 overload)
Error('bad')
  }
  return new 
var Promise: PromiseConstructor
new <unknown>(executor: (resolve: (value: unknown) => void, reject: (reason?: any) => void) => void) => Promise<unknown>
Creates a new Promise.
@param ― executor A callback used to initialize the promise. This callback is passed two arguments:
a resolve callback used to resolve the promise with a value or the result of another promise,
and a reject callback used to reject the promise with a provided reason or error.
Promise((
resolve: (value: unknown) => void
resolve, 
reject: (reason?: any) => void
reject) => {
    /* ... */
  })
}

const res = await 
toResult<unknown>(promise: PromiseLike<unknown>): Promise<Result<unknown>>
Converts a PromiseLike to a Promise<Result>.
Note: If the given promise throws a non-Error value, it will be
rethrown.
@see ― https://radashi.js.org/reference/async/toResult
@example 
import { toResult, Result } from 'radashi'

const good = async (): Promise<number> => 1
const bad = async (): Promise<number> => { throw new Error('bad') }

const goodResult = await toResult(good())
// => [undefined, 1]

const badResult = await toResult(bad())
// => [Error('bad'), undefined]
@version ― 12.4.0
toResult(
function bad(): Promise<unknown>
bad())
const res: Result<unknown>