pull-postmsg-stream

Pull streams over window.postMessage

It provides the two parts of a through stream: a source stream and a sink stream that can be used together to stream data over window.postMessage.

Install

npm install pull-postmsg-stream

Usage

To use pull-postmsg-stream you need two window objects. One of the window objects has the data, the other wants the data. Under the hood, pull-postmsg-stream uses postmsg-rpc. If you're not familiar with it, it's a good idea to read up on how it works before continuing!

In the first window (the one that has the data):

const pull = require('pull-stream')
const PMS = require('pull-postmsg-stream')

pull(
  pull.values([/* your data */]),
  PMS.sink('read', {/* options passed to postmsg-rpc expose */})
)

In the second window (the one that wants the data):

const pull = require('pull-stream')
const PMS = require('pull-postmsg-stream')

pull(
  PMS.source('read', {/* options passed to postmsg-rpc caller */}),
  pull.collect(console.log) // Collects and logs out your data
)

1. Window that has the data calls PMS.sink, which exposes a function called "read" & returns a sink stream
2. Window that wants the data calls PMS.source, which creates a caller function for "read" & returns a source stream
3. In the window that wants the data, the pull(...) pipeline starts the flow of data from the PMS.source stream
4. When data is requested from the PMS.source stream, it calls the exposed "read" function
5. This causes the PMS.sink stream in the window that has the data to pull out of pull.values and return it all the way back to pull.collect in the window that wants the data

See the example for complete code.

Example

To build and run the example, run the following in your terminal:

git clone https://github.com/tableflip/pull-postmsg-stream.git
cd pull-postmsg-stream
npm install
npm run example

Then open your browser at http://localhost:3000

API

PMS.sink(readFnName, options)

Creates a new sink stream for exposing data to be pulled over postMessage.

• readFnName - the name of the function that postmsg-rpc will expose for a PMS.source stream to read from
• options - options passed directly to postmsg-rpc expose, see docs here
  • options.post - function to call after read, see docs here

Note that if you're going to create multiple streams, you'll need to generate a new readFnName for each stream and somehow communicate that to your other window so that it can create a PMS.source that reads from the correct place.

PMS.source(readFnName, options)

Creates a new source stream for pulling data over postMessage.

• readFnName - the same name that was passed to PMS.sink, allowing the source to read from the sink
• options - options passed directly to postmsg-rpc caller, see docs here
  • options.post - function to call after read, see docs here

Contribute

Feel free to dive in! Open an issue or submit PRs.

License

MIT © Alan Shaw