Cross domain post-messaging on the client side, using a simple listener/client pattern.
Send a message to another window, and:
- Get a response from the window you messaged
- Pass functions to another window, across different domains
- Handle any errors that prevented your message from getting through
- Don't worry about serializing your messages; just send javascript objects
- Use promises, callbacks or async/await to wait for responses from windows you message
- Set up a secure message channel between two windows on a certain domain
- Send messages between a parent and a popup window in IE
postRobot.on('getUser', function(event) {
return {
id: event.data.id,
name: 'Zippy the Pinhead'
};
});
postRobot.send(someWindow, 'getUser', { id: 1337 }).then(function(event) {
console.log(event.source, event.origin, 'Got user:', event.data.name);
}).catch(function(err) {
console.error(err);
});
postRobot.on('getUser', function(event) {
return getUser(event.data.id).then(function(user) {
return {
name: user.name
};
});
});
postRobot.on('getUser', { id: 1337 }, function(event, callback) {
setTimeout(function() {
callback(null, {
id: event.data.id,
name: 'Captain Pugwash'
});
}, 500);
});
postRobot.once('init', function(event) {
return {
name: 'Noggin the Nog'
};
});
postRobot.on('init', { window: window.parent }, function(event) {
return {
name: 'Guybrush Threepwood'
};
});
postRobot.on('init', { domain: 'http://zombo.com' }, function(event) {
return {
name: 'Manny Calavera'
};
});
postRobot.send(someWindow, 'getUser', { id: 1337 }, { timeout: 5000 }).then(function(event) {
console.log(event.source, event.origin, 'Got user:', event.data.name);
}).catch(function(err) {
console.error(err);
});
postRobot.send(someWindow, 'getUser', { id: 1337 }, { domain: 'http://zombo.com' }).then(function(event) {
console.log(event.source, event.origin, 'Got user:', event.data.name);
});
postRobot.sendToParent('getUser').then(function(event) {
console.log(event.data);
});
postRobot.on('getUser', async ({ source, origin, data }) => {
let user = await getUser(data.id);
return {
id: data.id,
name: user.name
};
});
try {
let { source, origin, data } = await postRobot.send(someWindow, `getUser`, { id: 1337 });
console.log(source, origin, 'Got user:', data.name);
} catch (err) {
console.error(err);
}
For security reasons, it is recommended that you always explicitly specify the window and domain you want to listen to and send messages to. This creates a secure message channel that only works between two windows on the specified domain:
postRobot.on('getUser', { window: childWindow, domain: 'http://zombo.com' }, function(event) {
return {
id: event.data.id,
name: 'Frodo'
};
});
postRobot.send(someWindow, 'getUser', { id: 1337 }, { domain: 'http://zombo.com' }).then(function(event) {
console.log(event.source, event.origin, 'Got user:', event.data.name);
}).catch(function(err) {
console.error(err);
});
You can even set up a listener and sender instance in advance:
var listener = postRobot.listener({ window: childWindow, domain: 'http://zombo.com' });
listener.on('getUser', function(event) {
return {
id: event.data.id,
name: 'Frodo'
};
});
var client = postRobot.client({ window: someWindow, domain: 'http://zombo.com' });
client.send('getUser', { id: 1337 }).then(function(event) {
console.log(event.source, event.origin, 'Got user:', event.data.name);
}).catch(function(err) {
console.error(err);
});
Post robot lets you send across functions in your data payload, fairly seamlessly.
For example:
postRobot.on('getUser', function(event) {
return {
id: event.data.id,
name: 'Nogbad the Bad',
logout: function() {
currentUser.logout();
}
};
});
postRobot.send(myWindow, { id: 1337 }, 'getUser').then(function(event) {
var user = event.data;
user.logout().then(function() {
console.log('User was logged out');
});
});
The function user.logout()
will be called on the original window. Post Robot transparently messages back to the
original window, calls the function that was passed, then messages back with the result of the function.
Because this uses post-messaging behind the scenes and is therefore always async, user.logout()
will always return a promise, and must be .then
'd or await
ed.
Unfortunately, IE blocks direct post messaging between a parent window and a popup, on different domains.
In order to use post-robot in IE9+ with popup windows, you will need to set up an invisible 'bridge' iframe on your parent page:
[ Parent page ]
+---------------------+ [ Popup ]
| xx.com |
| | +--------------+
| +---------------+ | | yy.com |
| | [iframe] | | | |
| | | | | |
| | yy.com/bridge | | | |
| | | | | |
| | | | | |
| | | | | |
| | | | +--------------+
| +---------------+ |
| |
+---------------------+
a. Create a bridge path on the domain of your popup, for example http://yy.com/bridge.html
, and include post-robot:
<!-- http://yy.com/bridge.html -->
<script src="http://yy.com/js/post-robot.js"></script>
b. In the parent page, xx.com
, which opens the popup, include the following javascript:
<!-- http://xx.com -->
<script>
postRobot.openBridge('http://yy.com/bridge.html');
</script>
c. Now xx.com
and yy.com
can communicate freely using post-robot, in IE.