dennis-johnson-dev / sequential-promises

Sequentially resolve promises

Resolving ES2015 Promises sequentially

Running the tests

npm install
npm test

Note: examples in coffeescript

getResultsInSequence(promises, timeout)

Given an array of promises, resolve each promise serially and depending on a given timeout

promises: required - array of promises
timeout: optional - milliseconds between resolves

Example:

arrayOfPromises = [Promise.resolve(42), Promise.resolve(39)]

getResultsInSequence(arrayOfPromises).then((results) ->
  return results
)

// results = [42, 39]

Nested Promises

You can use any method you like to create an array of promises. This can be beneficial if you would like to do things such as:

nestedPromises = [Promise.resolve(42), Promise.resolve(39)]
arrayOfPromises = [Promise.all(nestedPromises), Promise.resolve(1)]

getResultsInSequence(arrayOfPromises).then((results) ->
  return results
)

// results = [[42, 39], 1]

This means you batch your promises however you like.

Using a timeout

If you need to resolve each promise after an interval, you can pass a timeout value. The method will wait the timeout before resolving each promise. If you have 10 promises and pass a timeout of 1000, it will take 10 seconds before the function returns.

promises = [Promise.resolve(42), Promise.resolve(39)]
arrayOfPromises = [Promise.all(promises), Promise.resolve(1)]
timeout = 1000

getResultsInSequence(arrayOfPromises, timeout).then((results) ->
  return results
)

// results after 2 seconds = [[42, 39], 1]