The close() method of the EventSource interface closes the connection, if one is made, and sets the EventSource.readyState attribute to 2 (closed). 
Note: If the connection is already closed, the method does nothing.
 The close() method of the EventSource interface closes the connection, if one is made, and sets the EventSource.readyState attribute to 2 (closed). 
Note: If the connection is already closed, the method does nothing.
js
close()
None.
None (undefined).
js
const button = document.querySelector("button"); const evtSource = new EventSource("sse.php"); button.onclick = () => { console.log("Connection closed"); evtSource.close(); };
Note: You can find a full example on GitHub — see Simple SSE demo using PHP.
| Specification | 
|---|
| HTML Standard  # dom-eventsource-close-dev  | 
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
close | 
6 | 79 | 6 | No | 12 | 5 | 4.4 | 18 | 45 | 12 | 5 | 1.0 | 
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    https://developer.mozilla.org/en-US/docs/Web/API/EventSource/close