Traditionally, a web page has to send a request to the server to receive new data; that is, the page requests data from the server. With server-sent events, it's possible for a server to send new data to a web page at any time, by pushing messages to the web page. These incoming messages can be treated as Events + data inside the web page.
To learn how to use server-sent events, see our article Using server-sent events.
EventSource| Specification | Status | Comment |
|---|---|---|
| HTML Living Standard The definition of 'Server-sent events' in that specification. | Living Standard |
EventSource interface| Desktop | ||||||
|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | |
| Basic support | 6 | No | 6 | No | Yes | 5 |
| Available in workers | Yes | No | 53 | No | Yes | Yes |
EventSource() constructor |
9 | No | 6 | No | 11 | 5 |
close |
6 | No | 6 | No | Yes | 5 |
onerror |
6 | No | 6 | No | Yes | 5 |
onmessage |
6 | No | 6 | No | Yes | 5 |
onopen |
6 | No | 6 | No | Yes | 5 |
readyState |
6 | No | 6 | No | Yes | 5 |
url |
6 | No | 6 | No | Yes | 5 |
withCredentials |
6 | No | 6 | No | Yes | 5 |
| Mobile | |||||||
|---|---|---|---|---|---|---|---|
| Android webview | Chrome for Android | Edge Mobile | Firefox for Android | Opera for Android | iOS Safari | Samsung Internet | |
| Basic support | Yes | 18 | No | 45 | 12 | 5 | ? |
| Available in workers | Yes | Yes | No | 53 | Yes | Yes | ? |
EventSource() constructor |
Yes | 18 | No | 6 | 11 | 5 | ? |
close |
Yes | 18 | No | 45 | 12 | 5 | ? |
onerror |
Yes | 18 | No | 45 | 12 | 5 | ? |
onmessage |
Yes | 18 | No | 45 | 12 | 5 | ? |
onopen |
Yes | 18 | No | 45 | 12 | 5 | ? |
readyState |
Yes | 18 | No | 45 | 12 | 5 | ? |
url |
Yes | 18 | No | 45 | 12 | 5 | ? |
withCredentials |
Yes | 18 | No | 45 | 12 | 5 | ? |
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https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events