Accessing The Value Inside A Result

This library takes advantage of TypeScript's type-guard feature.

By simply doing an if (using .isOk or .isErr) check on your result, you can inform the TypeScript compiler of whether you have Ok instance, or an Err instance, and subsequently you can get access to the value or error value in the respective instances.

Example:

import { ok, err } from 'neverthrow'

const example1 = ok(123)
const example2 = err('abc')

if (example1.isOk()) {
  // you now have access to example1.value
  doSomethingUseful(example1.value)
} else {
  // you now have access to example1.error
  handleError(example1.error)
}

if (example2.isErr()) {
  // you now have access to example2.error
  handleError(example2.error)
} else {
  // you now have access to example2.value
  doSomethingUseful(example2.value)
}