HTML

The onmessage Event in HTML DOM used when an object has received some message through an event source. The event object for onmessage Event supports the following schemes:

data: It contains the actual message present inside it.
origin: It contains the URL of the document that invoked the event.
lastEventId: It works as descriptive attribute for the last message that was spotted in the message stream.

Note: Server-Sent Events are not supported in Internet Explorer.

Syntax:

object.onmessage = function(){myScript};

Using the addEventListener() method

object.addEventListener("message", myScript);

Example 1:

<!DOCTYPE html>
<html>
  
<head>
    <title>
        HTML DOM onmessage Event
    </title>
</head>
 
<body>
    <h1 id="gfg"></h1>
    <div id="Beginner"></div>
      
    <!--Main Function-->
    <script>
        if (typeof(EventSource) !== "undefined") {
            var source = new EventSource("/html/demo_sse.php");
            source.onopen = function() {
                document.getElementById("gfg").innerHTML =
                                               "w3wiki";
            };
  
            source.onmessage = function(event) {
                document.getElementById("Beginner").innerHTML += 
                                           event.data + "<br>";
            };
  
        }
        else {
            document.getElementById("Beginner").innerHTML = 
                                    "browser does not support";
        }
    </script>
</body>
  
</html>

Output:

Example 2: Using the addEventListener() method

javascript

<!DOCTYPE html>
<html>
  
<head>
    <title>
        HTML DOM onmessage Event
    </title>
</head>
  
<body>
    <h1 id="gfg"></h1>
    <div id="Beginner"></div>
      
    <!--main Function-->
    <script>
        if (typeof(EventSource) !== "undefined") {
            var source = new EventSource("/html/demo_sse.php");
            source.addEventListener("open", function() {
                document.getElementById("gfg").innerHTML =
                                               "w3wiki";
            });
  
            source.addEventListener("message", function(event) {
                document.getElementById("Beginner").innerHTML += 
                                           event.data + "<br>";
            });
  
        } else {
            document.getElementById("Beginner").innerHTML = 
                             "Your browser does not supported";
        }
    </script>
  
</body>
  
</html>

Output:

Supported browsers: The browser supported by onmessage Event are listed below:

Google Chrome 60.0
Edge 12.0
Mozilla Firefox 9.0
Internet Explorer 8.0
Apple Safari 4.0
Opera 47.0

HTML | DOM onmessage Event

html

javascript

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