What is a promise in JavaScript?

In JavaScript, a promise is an object that represents the eventual completion or failure of an asynchronous operation and its resulting value. This means that a promise serves as a placeholder for a value that is not immediately available but will be resolved in the future, whether successfully or with an error.

When you create a promise, it can be in one of three states: pending, fulfilled, or rejected. When the asynchronous task completes successfully, the promise is fulfilled, and the resolved value can be accessed using the .then() method. Conversely, if the task fails, the promise is rejected, and the error can be handled using the .catch() method. This pattern allows developers to write cleaner and more manageable code dealing with asynchronous processes, enabling them to avoid callback hell and move towards a more readable chain of operations.

The other options do not accurately define what a promise is in JavaScript. The first option incorrectly describes a specific data type that does not exist in standard JavaScript. The third option refers to returning multiple values, which can be achieved in JavaScript using arrays or objects, but not through promises specifically. The last option suggests that a block of code executes only once, which could refer to functions or similar constructs but does not capture the nature of