Hermes-messenger NPM

Small wrapper on top of Cross Origin postMessage

Install

Bower

$ bower install --save hermes-messenger

Browserify

$ npm install --save hermes-messenger

Docs

This exports or adds to window.HermesMessenger a constructor to create a new instance.

Constructor

var Hermes = require('hermes-messenger');
new Hermes(frame, origin);

frame is the window of the Iframe or Frame Node Element (e.g. document.querySelector('iframe').contentWindow)
- If not set, can't send messages but can still receive & respond
origin is the url (with protocol) of the frame (e.g. https://gojobhero.com) or * for any origin
- If not set, would default to *.
- Always specify an exact target origin, not *. A malicious site can change the location of the window without your knowledge, and therefore it can intercept the data sent.

Look at MDN postMessage for more info.

Send

Send a messsage to the frame. data can be anything.

hermes.send(data);

If you want to recieve a response pass a Node style callback as the 2nd param.

hermes.send({ msg: 'Yay rainbows!'}, function(err, resp) { });
hermes.send('Yay stringy rainbows!', function(err, resp) { });

Receive

Listen on the message event.

The function takes the params:

data that was received
callback if the sender wants a reply. Node style.
source source message came from
origin origin message came from

hermes.on('message', function(data, cb, source, origin) { });

You can check if you need to reply back to this message by checking if a 2nd argument is passed, the callback.

hermes.on('message', function(data, callback) {
  var someErr = true;
  if (callback) {
    if (someErr) {
      cb('some err');
    } else {
      cb(null, 'ponies');
    }
  }
});

Usage

var Hermes = require('hermes-messenger'); // If using Browserify
var Hermes = window.HermesMessenger;      // Also exports onto window

// Only has ability to recieve/respond to https://gojobhero.com
var hermes = new Hermes(null, 'https://gojobhero.com');

var hermes = new Hermes(document.querySelector('iframe').contentWindow, '*');


// Send a message to an iframe
hermes.send({ message: 'Testing Rainbows!' });

// Send a message and wait for a response
hermes.send({
  message: 'How many rainbows?!'
}, 
function(err, data) {});


// Listen for messages
hermes.on('message', function(data) {
});

// Listen for messages and respond
hermes.on('message', function(data, cb) {
  var err = false;

  if (cb) {
    if (err) {
      cb('Error getting data'); // Send error
    } else {
      cb(null, 'All of the rainbows');
    }
  }
});