How to Pause JavaScript Execution While Waiting for a Condition

Learn how to effectively pause JavaScript execution until a specific condition is met using Promises and Async/Await.
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How to Pause JavaScript Execution While Waiting for a Condition

In the world of JavaScript, efficient handling of asynchronous tasks is crucial, especially when dealing with operations that depend on certain events firing or conditions being met. A common scenario developers face is needing to pause execution until a specific event or condition is true. For instance, when integrating with third-party SDKs or APIs, you may need to wait for one operation to finish before proceeding to the next.

The Problem: Coordination Between Functions

Let’s take a look at an example scenario. Imagine you have two functions, Func1 and Func2, where their execution is tied to specific events. You want Func2 to run only after Func1 has completed its work. Initially, your code uses a poll-and-wait technique through a while loop to check if Func1 has finished by examining a flag (window._connected). However, this approach can lead to inefficient code and potential performance issues.

Here's how your initial code structure looked:

[[See Video to Reveal this Text or Code Snippet]]

The key issue with this approach is that it blocks execution and may lead to performance problems and an unresponsive user interface.

The Solution: Using Promises and Async/Await

A cleaner and more modern approach involves using Promises and the async/await syntax, which allows you to structure your code neatly and avoid blocking the main execution thread. Here’s a refined version of the code utilizing these concepts.

Step 1: Create a Promise for the Condition

Instead of checking the condition in a loop, we can create a promise that resolves when window._connected changes.

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Utilize Async/Await in the Function

Now, you can declare your goToNextWindow function as an asynchronous function, which allows you to use the await keyword to pause execution until the promise is resolved.

[[See Video to Reveal this Text or Code Snippet]]

Benefits of This Approach

Non-blocking Execution: Using Promises allows the execution of your JavaScript to continue without blocking the thread, keeping the user interface responsive.

Cleaner Code: The use of async/await makes the flow of your program easier to read and understand.

Error Handling: You can implement error handling more effectively using try-catch blocks around your asynchronous calls.

Conclusion

By transitioning your code to use Promises and async/await, you can effectively manage asynchronous operations in JavaScript, making your code more efficient and readable. This method not only enhances performance but also allows for cleaner and more maintainable code. So the next time you find yourself needing to wait for a condition, consider using the techniques discussed above!

Happy coding!