Salesforce JavaScript Developer Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

Promises are a key feature in JavaScript that facilitate the management of asynchronous operations in a more organized and readable manner compared to earlier approaches like callbacks. They represent a value that may be available now, or in the future, or never, allowing developers to write code that can handle eventual results of asynchronous tasks.

When a Promise is created, it can be in one of three states: pending, fulfilled, or rejected. This state management allows for clear endpoints in the execution flow; once the operation is completed (either successfully or with an error), the Promise resolves, enabling further actions based on the outcome. This is typically done through `.then()` and `.catch()` methods, which enhance readability and maintainability of code by organizing logic around success and failure paths.

In contrast, callbacks are a more traditional mechanism for handling asynchronous operations, but they can lead to nested structures known as "callback hell," making the code difficult to read and maintain. Loops and variables do not inherently pertain to the asynchronous nature of JavaScript. Loops operate synchronously and are not suitable for managing tasks that need to run independently of the main execution thread. Variables, while fundamental to storing data in JavaScript, do not provide any mechanisms for handling asynchronous code flow.