Window postMessage API

The postMessage API involves two roles:

Sender Window: Sends a message to another window using postMessage().
Receiver Window: Listens for the message and processes the received data.

Receiver Window

Listens for messages with addEventListener('message')
Updates the paragraph content with the message

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Receiver</title>
</head>
<body>
    <p>Message will appear here</p>
    <script>
        // Listen for incoming messages
        window.addEventListener('message', (event) => {
            // Validate the source and process data
            document.querySelector('p').textContent = event.data;
        });
    </script>
</body>
</html>

Sender Window

Opens the receiver window with window.open().
Sends a message using postMessage() when the button is clicked

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Sender</title>
</head>
<body>
    <button onclick="sendMessage()">Send Message</button>
    <script>
        const receiverURL = "http://localhost/receiver.html";
        const childWindow = window.open(receiverURL);

        function sendMessage() {
            const message = "Hello, Receiver!";
            childWindow.postMessage(message, "*");
        }
    </script>
</body>
</html>

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Last updated 4 days ago

hashtagReceiver Window

hashtagSender Window

Receiver Window

Sender Window