Async programming, also known as asynchronous programming, is a programming paradigm that allows running operations asynchronously, without blocking the main execution thread. This is particularly useful for I/O-bound and high-latency operations, such as network communication, file I/O, and database access.

Key Concepts

  • Event Loop: The core of async programming is the event loop, which manages the execution of asynchronous tasks. When an operation is performed asynchronously, the control is returned to the event loop, which can then handle other tasks until the operation is completed.
  • Callbacks: Callbacks are functions that are passed as arguments to other functions and are executed after the function completes its task. They are often used in async programming to handle the completion of asynchronous operations.
  • Promises: Promises are objects representing the eventual completion (or failure) of an asynchronous operation and its resulting value. They are a more structured and flexible alternative to callbacks.
  • Async/Await: Async/await is a syntax that allows you to write asynchronous code that looks and behaves like synchronous code. It uses the async keyword to declare an asynchronous function and the await keyword to pause the execution of the function until the awaited promise is resolved.

Example

Here's a simple example of async programming using callbacks:

function fetchData(callback) {
  setTimeout(() => {
    callback('Data fetched');
  }, 2000);
}

fetchData((result) => {
  console.log(result); // Output: Data fetched
});

Resources

For more information on async programming, you can refer to the following resources:

JavaScript