onopen Event

Example

Create a new EventSource object, and specify the URL of the page sending the updates.
When (and if) a connection is established, output some text in a <h1> element:

var source = new EventSource("demo_sse.html");
source.onopen = function() {
document.getElementById("myH1").innerHTML = "Getting server updates";
};

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Description

The onopen event occurs when a connection with an event source is opened.

Related events:

onmessage - Occurs when a message is received
onerror - Occurs when a problem occurs

For more information about Server-Sent Events, read our HTML5 Server-Sent Events Tutorial.

Browser Support

The numbers in the table specify the first browser version that fully supports the event.

Event
onopen	9.0	Not supported	6.0	5.0	11.0

Syntax

object.onopen = function(){ myScript};

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Using the addEventListener() method:

object.addEventListener("open", myScript);

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Technical Details

Bubbles:	No
Cancelable:	No
Event type:	Event

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