JavaScript's single-threaded processing, which can cause performance issues when executing long-running code, is addressed through the introduction of the Web Workers API in HTML5, enabling parallel execution of JavaScript code within web browsers. This approach is demonstrated by developing a text analyzer that operates efficiently by employing web workers to handle tasks in separate threads, thus maintaining application responsiveness even with growing text size. The text details the implementation of web workers, including creating and managing threads, handling messages, and managing errors, while also discussing the limitations of web workers, such as their inability to access the DOM and the requirement for HTTP or HTTPS protocols. Additionally, the concept of shared workers is introduced to allow resource sharing among multiple pages or frames within the same domain, thereby optimizing resource usage across browser contexts.