send-channel-message

This package provide simple function that allow to pass messages to separate script in different browsing context and get back result data as a Promise using Channel Messaging API.

Motivation

If you just want to communicate with script in other window/iframe/worker, you can use postMessage function and onMessage event handler.

But if you want to communicate in Promise style, so thats a problem. And Channel Messaging API solves this problem using two-way channels with a port at each end.

Installation

Install the package to your project:

npm install --save send-channel-message

And then you can import the function:

• If you used ES modules:

  import sendChannelMessage from 'send-channel-message';

• If you used it in CommonJS environment (don’t forget to add .default to your import):

  var sendChannelMessage = require('send-channel-message').default;

• Additionally it's also support a UMD build:

  var sendChannelMessage = window.sendChannelMessage.default;

Usage

Basically it's a function that takes 3 inputs and return a Promise:

const promise = sendChannelMessage(message, target, origin);

When Promise resolves it return object with response data:

promise.then( (data) => {
    console.log(data);
});

Inputs

• message - data to be sent to the other script.

• target - a reference to the window/worker that will receive the message.

• origin - specifies what the origin of target must be for the event to be dispatched (default = "*").

*See postMessage syntax description.

Outputs

data property of the MessageEvent interface.

*See MessageEvent data description.

Example

You can create a module for communicating with some iFrame using send-channel-message like this:

/* iframeCommunicator.js */

import sendChannelMessage from 'send-channel-message';

const target = document.getElementById('someIframe').contentWindow;

function sendMessageToIframe(message) {
    return sendChannelMessage(message, target);
}

export default {
    initialize: (initData) => {
        const message = {
            type: 'INIT',
            initData
        };
        return sendMessageToIframe(message);
    },
    // ...
};

And then use it for simple send requests and receive responses in API-like style:

/* index.js */

import iframeCommunicator from './iframeCommunicator';

// ...

iframeCommunicator.initialize('very important data')
    .then( (data) => {
        console.log('Received init response:', data);
    });

// ...

The iFrame script will look something like this:

/* iframe.js */

window.addEventListener('message', ({ data, ports }) => {
    if (data && ports && ports[0]) {
        if (data.type === 'INIT') {
            console.log('Received init request:', data.initData);
            ports[0].postMessage('Init success!');
            ports[0].close();
        }
    }
});

Tests

Simply clone the repo and run

npm install

npm test

License

MIT