EventSource: EventSource() constructor

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨January 2020⁩.

Note: This feature is available inWeb Workers.

TheEventSource()constructor returns a newly-createdEventSource, which represents aremote resource.

Syntax

new EventSource(url)new EventSource(url, options)

Parameters

url

A string that represents the location of the remote resourceserving the events/messages.

optionsOptional

Provides options to configure the new connection. The possible entries are:

withCredentialsOptional: A boolean value, defaulting tofalse, indicatingif CORS should be set toinclude credentials.

Examples

const evtSource = new EventSource("sse.php");const eventList = document.querySelector("ul");evtSource.onmessage = (e) => {  const newElement = document.createElement("li");  newElement.textContent = `message: ${e.data}`;  eventList.appendChild(newElement);};

Note:You can find a full example on GitHub — seeSimple SSE demo using PHP.