Asynchronous programming should only be used in programming independent tasks, where it plays a critical role. For instance, asynchronous programs are ideal for development projects with a large number of iterations. Because steps don’t have to follow a fixed sequence, asynchronous programming keeps development moving forward.

Responsive UI is a great use case for asynchronous planning. Take, for example, a shopping app. When a user pulls up their order, the font size should increase. Instead of first waiting to load the history and update the font size, asynchronous programming can make both actions happen simultaneously.

When to use sync

Asynchronous programming is relatively complex. It can overcomplicate things and make code difficult to read. Synchronous programming, on the other hand, is fairly straightforward; its code is easier to write and doesn’t require tracking and measuring process flows (as async does). Because tasks are dependent on each other, there’s a need to know if they could run independently without interrupting each other.

Synchronous programming could be appropriate for a shopping app, for example. When checking out online, a user wants to buy all of their items together, not individually. Instead of completing an order every time the user adds something to their cart, synchronous programming ensures that the payment method and shipping destination for all items are selected at the same time.

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