How to Use JavaScript 'async'

JavaScript has a built-in async keyword that can be used to create asynchronous functions. Asynchronous functions are functions that can run in parallel with the rest of your code, and allow you to perform long-running operations without blocking the main execution thread.

To use the async keyword, you simply need to add it before the function keyword when defining a function. This converts the function into an asynchronous function, which can be used to write code that runs asynchronously.

For example, the code below defines an asynchronous function myAsyncFunction that performs a long-running operation:

async function myAsyncFunction() {
  // Perform long-running operation here
}

Once you have defined an asynchronous function, you can use the await keyword to pause the execution of the function until an asynchronous operation completes. This allows you to write asynchronous code that looks and behaves like synchronous code, making it easier to write and understand.

Here is an example that shows how to use await to pause the execution of an asynchronous function until a Promise is resolved:

async function myAsyncFunction() {
  const result = await someAsyncOperation()
  // Use the result of the async operation here
}

In the code above, the myAsyncFunction function is paused until the someAsyncOperation asynchronous operation completes. Once the operation completes, the result variable is assigned the resolved value of the Promise returned by someAsyncOperation.

Note that await can only be used inside an asynchronous function. Attempting to use it outside an asynchronous function will result in a syntax error.