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SharedWorker: SharedWorker() constructor

The SharedWorker() constructor creates a SharedWorker object that executes the script at the specified URL. This script must obey the same-origin policy.

Note: there is disagreement among browser manufacturers about whether a data URL is of the same origin or not. Although Firefox 10.0 and later accept data URLs, that's not the case in all other browsers.

Syntax

js

new SharedWorker(aURL)
new SharedWorker(aURL, name)
new SharedWorker(aURL, options)

Parameters

aURL

A string representing the URL of the script the worker will execute. It must obey the same-origin policy.

name Optional

A string specifying an identifying name for the SharedWorkerGlobalScope representing the scope of the worker, which is useful for creating new instances of the same SharedWorker and debugging.

options Optional

An object containing option properties that can set when creating the object instance. Available properties are as follows:

type

A string specifying the type of worker to create. The value can be classic or module. If not specified, the default used is classic.

credentials

A string specifying the type of credentials to use for the worker. The value can be omit, same-origin, or include. If not specified, or if type is classic, the default used is omit (no credentials required).

name

A string specifying an identifying name for the SharedWorkerGlobalScope representing the scope of the worker, which is mainly useful for debugging purposes.

Exceptions

SecurityError DOMException

Thrown if the document is not allowed to start workers, for example if the URL has an invalid syntax or if the same-origin policy is violated.

NetworkError DOMException

Thrown if the MIME type of the worker script is incorrect. It should always be text/javascript (for historical reasons other JavaScript MIME types may be accepted).

SyntaxError DOMException

Thrown if aURL cannot be parsed.

Examples

The following code snippet shows creation of a SharedWorker object using the SharedWorker() constructor and subsequent usage of the object:

js

const myWorker = new SharedWorker("worker.js");

myWorker.port.start();

first.onchange = () => {
  myWorker.port.postMessage([first.value, second.value]);
  console.log("Message posted to worker");
};

second.onchange = () => {
  myWorker.port.postMessage([first.value, second.value]);
  console.log("Message posted to worker");
};

myWorker.port.onmessage = (e) => {
  result1.textContent = e.data;
  console.log("Message received from worker");
};

For a full example, see our Basic shared worker example (run shared worker.)

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
SharedWorker 5 79 29 No 10.6 165–7 No No 33 11–14 165–7 4.0–5.0
ecmascript_modules 80 80 114 No 67
15["Nested workers support was introduced in Safari 15.5.", "Script loading in nested workers was introduced in Safari 16.4."]
No No 114 No
15["Nested workers support was introduced in Safari 15.5.", "Script loading in nested workers was introduced in Safari 16.4."]
No
mime_checks No No 81 No No 16 No No 81 No 16 No
options_name_parameter 70 79 55 No 57 No No No 55 No No No

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/SharedWorker/SharedWorker