Which of the following is true regarding asynchronous code in JavaScript?

The statement that asynchronous code in JavaScript can improve performance by not blocking the main thread is true. Asynchronous code allows certain operations, such as fetching data from a server or executing long-running tasks, to be performed without halting the execution of other code. This is crucial in maintaining a smooth user experience, particularly in web applications where responsiveness is key.

When asynchronous operations are in place, the main thread remains free to handle user interactions, rendering updates, and other tasks while waiting for the asynchronous operation to complete. This is typically achieved through the use of callbacks, promises, or the async/await syntax, which allows the JavaScript engine to continue processing other code rather than getting stuck waiting for a result.

This aspect of asynchronous programming is particularly important for applications that require real-time interactions or need to handle multiple tasks simultaneously without showing delays to the user. Therefore, the ability to run non-blocking operations is foundational to effective JavaScript application development.