How many threads are in JavaScript?

In JavaScript in the browser, there is by default a single main thread of execution — the main thread, where all code, rendering, and event handling are performed.

However, with the advent of Web Workers, it is possible to create additional background threads to perform tasks without blocking the main thread. But these workers operate in isolation and do not have direct access to the DOM.

Thus, it can be said that JavaScript is single-threaded by nature, but with the help of Web Workers, multiple threads can be used for parallel processing.