Sending Data to Another Domain using postMessage

• Download source code (CrossDomainDataSharing.rar)
• Download source code (receiver.rar)

In this post, we will see how we can send data to another domain from our application. You can simply call it as a cross domain data sharing. In few cases, we may need to send some data which is needed for our other domain or application to work as expected. I had some cases in my programming life. I have done this requirement with the help of postMessage method. The window.postMessage method helps us to enable cross-origin communication. I hope you will like this.

Background

I was forced to maintain some cookies in my second application every time. That too, I wanted to set the same from my first application. So I implemented this with the help of window.postMessage. For demo purposes, here I am creating two applications:

• CrossDomainDataSharing
• Receiver

Using the Code

First, we will concentrate on the CrossDomainDataSharing application in which we are sending our data to Receiver application.

To start with, you need to add jQuery reference to your page. And to make this application trendy, I have added Smart Alert to our application, you can see the needed references and styles below.

<script src="Scripts/jquery-2.2.0.min.js"></script>
    <script src="js/alert.min.js"></script>
    <link href="css/alert.min.css" rel="stylesheet" />
    <link href="themes/dark/theme.css" rel="stylesheet" />

Next thing is “Calling Window On Load” Function.

window.onload = function () {
           document.getElementById('btnSend').addEventListener('click', sendData);
       };

Here, we are just adding a click event to the button with id btnSend. Before going to add the event, please make sure that you have created a button.

<button id="btnSend">Send Feedback</button>

The next thing is to create an iframe and load our second application link to that by giving src value.

<iframe id="ifrLoad"
src="http://localhost:55592/Receiver/Cross-Domain-Data-Sharing-Receiver.html"
   style="display: none;">
       <p>Oops!. Your browser does not support iframes.</p>
   </iframe>

Have you noticed that we have called a function called sendData. Let us see what that function does.

function sendData(e) {
            try {
                $.alert.open('prompt', 'Please send your feedback!.', function (button, value) {
                    if (button == 'ok') {
                        e.preventDefault();;
                        var myIfr = window.frames['ifrLoad'].contentWindow;
                        myIfr.postMessage(value, 'http://localhost:55592/Receiver/Cross-Domain-Data-Sharing-Receiver.html')
                        $.alert.open('Thank you so much for your feedback.' || 'No value has been entered');
                    }
                });

            } catch (e) {
                console.log('Error: ' + e.message);
            }
        }

We are creating a smart alert first if the user says ‘Ok’, we will just pass the given feedback to our second application with the help of postMessage method. The implementation is pretty simple. Isn’t it?

You can style the button you have created as follows:

<style>
        #btnSend {
            margin-left: 11px;
            border: solid 1px #000;
            padding: 9px 22px 7px;
            min-width: 32px;
            font-weight: bold;
            line-height: 13px;
            color: #fff;
            text-shadow: 0 1px 1px rgba(0, 0, 0, 0.5);
            background-color: #232323;
            background-image: linear-gradient(#2b2b2b 1%, #1d1d1d 99%);
            background-image: -webkit-linear-gradient(#2b2b2b 1%, #1d1d1d 99%);
            background-image: -moz-linear-gradient(#2b2b2b 1%, #1d1d1d 99%);
            background-image: -o-linear-gradient(#2b2b2b 1%, #1d1d1d 99%);
            background-image: -ms-linear-gradient(#2b2b2b 1%, #1d1d1d 99%);
            -pie-background: linear-gradient(#2b2b2b 1%, #1d1d1d 99%);
            border-radius: 3px;
            -webkit-border-radius: 3px;
            -moz-border-radius: 3px;
            -ms-border-radius: 3px;
            box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
            0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
            -webkit-box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
            0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
            -moz-box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
            0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
            -ms-box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
            0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
            -o-box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
            0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
        }

            #btnSend:hover {
                background-color: #404040;
                background-image: linear-gradient(#515151 1%, #2e2e2e);
                background-image: -webkit-linear-gradient(#515151 1%, #2e2e2e);
                background-image: -moz-linear-gradient(#515151 1%, #2e2e2e);
                background-image: -o-linear-gradient(#515151 1%, #2e2e2e);
                background-image: -ms-linear-gradient(#515151 1%, #2e2e2e);
                -pie-background: linear-gradient(#515151 1%, #2e2e2e);
                box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
                0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
                -webkit-box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
                0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
                -moz-box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
                0 1px rgba(255, 255, 255, 0.07) inset, 
                0 0 0 1px rgba(255, 255, 255, 0.06) inset;
                -ms-box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
                0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
                -o-box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
                0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
            }
    </style>

Now that is all for the sending part, please see the complete code for our first application here.

<!DOCTYPE html>
<html>
<head>
    <title>Cross Domain Data Sharing Demo - Sibeesh Passion</title>
    <script src="Scripts/jquery-2.2.0.min.js"></script>
    <script src="js/alert.min.js"></script>
    <link href="css/alert.min.css" rel="stylesheet" />
    <link href="themes/dark/theme.css" rel="stylesheet" />
    <style>
        #btnSend {
            margin-left: 11px;
            border: solid 1px #000;
            padding: 9px 22px 7px;
            min-width: 32px;
            font-weight: bold;
            line-height: 13px;
            color: #fff;
            text-shadow: 0 1px 1px rgba(0, 0, 0, 0.5);
            background-color: #232323;
            background-image: linear-gradient(#2b2b2b 1%, #1d1d1d 99%);
            background-image: -webkit-linear-gradient(#2b2b2b 1%, #1d1d1d 99%);
            background-image: -moz-linear-gradient(#2b2b2b 1%, #1d1d1d 99%);
            background-image: -o-linear-gradient(#2b2b2b 1%, #1d1d1d 99%);
            background-image: -ms-linear-gradient(#2b2b2b 1%, #1d1d1d 99%);
            -pie-background: linear-gradient(#2b2b2b 1%, #1d1d1d 99%);
            border-radius: 3px;
            -webkit-border-radius: 3px;
            -moz-border-radius: 3px;
            -ms-border-radius: 3px;
            box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
            0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
            -webkit-box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
            0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
            -moz-box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
            0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
            -ms-box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
            0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
            -o-box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
            0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
        }

            #btnSend:hover {
                background-color: #404040;
                background-image: linear-gradient(#515151 1%, #2e2e2e);
                background-image: -webkit-linear-gradient(#515151 1%, #2e2e2e);
                background-image: -moz-linear-gradient(#515151 1%, #2e2e2e);
                background-image: -o-linear-gradient(#515151 1%, #2e2e2e);
                background-image: -ms-linear-gradient(#515151 1%, #2e2e2e);
                -pie-background: linear-gradient(#515151 1%, #2e2e2e);
                box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
                0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
                -webkit-box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
                0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
                -moz-box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
                0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
                -ms-box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
                0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
                -o-box-shadow: 0 1px rgba(2, 3, 3, 0.5), 
                0 1px rgba(255, 255, 255, 0.07) inset, 0 0 0 1px rgba(255, 255, 255, 0.06) inset;
            }
    </style>
    <script>
        window.onload = function () {
            document.getElementById('btnSend').addEventListener('click', sendData);
        };
        function sendData(e) {
            try {
                $.alert.open('prompt', 
                'Please send your feedback!.', function (button, value) {
                    if (button == 'ok') {
                        e.preventDefault();;
                        var myIfr = window.frames['ifrLoad'].contentWindow;
                        myIfr.postMessage(value, 
                        'http://localhost:55592/Receiver/Cross-Domain-Data-Sharing-Receiver.html')
                        $.alert.open('Thank you so much for your feedback.' || 
                        'No value has been entered');
                    }
                });

            } catch (e) {
                console.log('Error: ' + e.message);
            }
        }
    </script>
</head>
<body>
    <button id="btnSend">Send Feedback</button>
    <iframe id="ifrLoad" 
    src="http://localhost:55592/Receiver/Cross-Domain-Data-Sharing-Receiver.html" 
    style="display: none;">
        <p>Oops!. Your browser does not support iframes.</p>
    </iframe>
</body>
</html>

Now we will concentrate on our second application ‘Receiver‘.

We will just add a window load function with event listener which accepts the data from our first application. Please see the following code for further clarification.

$(window).load(function () {
           window.addEventListener('message', addData);
           function addData(e) {
               document.cookie = "myData=" + e.data;
           };
       });

Here, myData is the cookie name.

You can see the complete code for our second application here.

<!DOCTYPE html>
<html>
<head>
    <title>Cross Domain Data Sharing Receiver - Sibeesh Passion</title>
    <script src="Scripts/jquery-2.2.0.min.js"></script>
    <script>
        $(window).load(function () {
            window.addEventListener('message', addData);
            function addData(e) {
                document.cookie = "myData=" + e.data;
            };
        });
    </script>
</head>
<body>
</body>
</html>

Now it is time to see our output.

Output

While sending the data to our second application.

While receiving the data in our second application.

That is all. We did it. Have a happy coding.

Conclusion

Did I miss anything that you may think is needed? Have you ever wanted to do this requirement? Could you find this post useful? I hope you liked this article. Please share me your valuable suggestions and feedback.

Your Turn. What Do You Think?

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