19. What is WebWorker?

Web Workers are a feature in web development that allows running JavaScript code in the background, separate from the main thread of your web application.

In traditional web applications, JavaScript code runs on the main thread, which is also responsible for rendering the user interface. This can lead to performance issues if your code is computationally intensive and causes the UI to freeze. Web Workers enable running scripts on separate threads, preventing the main thread from being blocked.

The multithreading nature of Web Workers ensures that the user interface remains responsive while tasks are executed in the background. Users can interact with the application without delays caused by intensive computations.

Moreover, by offloading resource-intensive tasks to Web Workers, you significantly enhance the performance of your web application. Web Workers can be utilized for tasks such as data processing, encryption, or image manipulation without slowing down the user interface.

Isolation: Web Workers operate in an isolated environment, separate from the main application. This isolation helps avoid conflicts and errors stemming from shared variables or dependencies. Additionally, it enhances security because malicious code in a worker won't directly impact the main application.

Web Workers exist in two variants:

1. Dedicated Web Workers: These workers are dedicated to a single script instance and can communicate with the main thread using the postMessage messaging system. They are typically used for tasks that require state preservation or more complex interactions.
2. Shared Web Workers: Shared Workers can be accessed from multiple windows or tabs of the same site. They are useful when you need to share data or state among different parts of your web application.

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