How to Properly Wait for a Function to Finish Before Calling It Again in JavaScript

Learn how to ensure that your JavaScript functions execute in the right order using async/await and promises, avoiding timing issues with function calls.
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How to Properly Wait for a Function to Finish Before Calling It Again in JavaScript

If you've ever encountered frustration while trying to control the timing of function calls in JavaScript, you're not alone. A common issue arises when dealing with asynchronous operations, particularly when using setTimeout. This can lead to unexpected results, such as jumbled output when trying to execute animations or other timed functions. In this guide, we'll dive into how to properly wait for a function to finish before calling it again, providing you with a reliable solution to this problem.

The Problem: Functions Calling Each Other Too Quickly

The primary concern is illustrated with this example code, where the TypeAnimation function is invoked twice in quick succession, causing unintended behavior in the output. For instance, when calling:

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

You may encounter outputs like "finrset xlitne olf itenxte of text but slower". This happens because the two calls overlap in their execution timing due to the asynchronous nature of setTimeout, leading to a mixed-up character display.

Exploring the Solution: Using Promises and Async/Await

Key Concepts

Promises: A promise is an object representing the eventual completion or failure of an asynchronous operation.

Async/Await: Introduced in ES8, the async/await syntax allows us to write asynchronous code that looks synchronous, making it easier to read and maintain.

The Correct Implementation

To ensure that TypeAnimation completes its execution before the next call is made, we can employ the following strategy:

Modify the TypeAnimation Function: Return a promise that resolves after the animation completes.

Use async/await in Calls: Await each function call to ensure they run sequentially.

Here's the corrected version of the code:

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

Adding HTML for Output

To ensure that our JavaScript has a target element to manipulate, make sure to include this HTML:

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

Explanation of the Changes

Returning Promises: The wait function creates a delay using a promise. This is essential to pause the execution.

Sequential Execution: By awaiting each TypeAnimation call, we ensure that each animation finishes before the next one starts.

Conclusion

Now, go ahead and implement this solution in your projects to see the difference! Feel free to share your thoughts or any other challenges you might face in the comments below.