What limitations exist for Web Worker threads?

Web Worker threads have the following limitations:

• No access to DOM: Web Workers cannot directly manipulate the document structure as they run in a separate context without access to the window object.
• No access to some window objects: They do not have access to objects like localStorage, XMLHttpRequest directly (though there are ways to bypass this via fetch or data passing), alert, confirm, prompt, and others related to the user interface.
• No direct access to parent context: They cannot directly access variables and functions from the script that created the Web Worker. Interaction is done via messages (postMessage).
• Data transfer only via serialization: Data between the main thread and Web Worker is transferred by copying (structured cloning). This means transmitted objects must be serializable.
• Scripts can only be loaded from the same domain: Web Workers can load scripts only from the same domain from which the main script was loaded (Same-origin policy). Service Workers are an exception.
• Limited number: There is a limit on the number of Web Workers that can run simultaneously, depending on the browser and system resources.
• No access to some APIs: Some browser APIs are unavailable in Web Workers, e.g., WebGL (though there are experimental implementations like OffscreenCanvas).