Chain

Provides a promise-like object that allows method chaining without memory or computation overhead.

Example

import chain from '@eyalsh/chain/lib/index.js'

const c = chain('foo')
  .with(console.log, e => console.error(e.message)) // Stdout: foo
  .then(function(v) {
    throw new Error(v);
  })
  .with(console.log, e => console.error(e.message)) // Stderr: foo
  .catch(() => 'bar')
  .finally(() => console.log('will always run'));

console.log(c); // Output: Chain {current: "bar", reason: null}
console.log(c.eject()); // Output: bar

c.then(v => {throw new Error(v)});

try {
  c.eject()
} catch (e) {
  console.error(e.message) // Stderr: bar
}

API

chain(current?, reason?) or new Chain(current?, reason?)

Creates a new Chain object with either a value or a rejection reason.

Chain.then(onfulfilled?, onrejected?): Chain

Applies modifications on the current value or rejection reason.
Reject a chain by throwing an error in either callbacks.

Chain.catch(onrejected?): Chain

Toggles a chain from rejected state to fulfilled state and applies modification on the rejection reason.
Reject a chain by throwing an error in the callback.

Chain.with(onfulfilled?, onrejected?): Chain

Performs side-effects with the current value or rejection reason.
These callbacks do not replace the current value or rejection and reason, and cannot toggle a chain state.

Chain.eject(): any

Returns the current value of the chain, or throws an error with the rejection reason if rejected.