How to Ensure If Statements Run After Function Calls in JavaScript

Discover how to handle asynchronous programming in JavaScript using Promises and async/await to ensure proper execution order in your code.
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This video is based on the question https://stackoverflow.com/q/69077062/ asked by the user 'OliT' ( https://stackoverflow.com/u/16296032/ ) and on the answer https://stackoverflow.com/a/69077370/ provided by the user 'Sadegh' ( https://stackoverflow.com/u/3509548/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Ensure If Statements Run After Function Calls in JavaScript

As a novice in the world of JavaScript and Node.js, you might find yourself grappling with an issue that many newcomers face: handling asynchronous code properly. This guide addresses a common scenario where you want an if statement to execute only after certain functions have completed their operations. If you’re facing issues with undefined values due to asynchronous function calls, keep reading!

The Problem: Running the If Statement Prematurely

Imagine you have two functions that fetch cryptocurrency prices from different APIs:

binancePrice() - Fetches the price of Bitcoin from Binance.

coinbasePrice() - Fetches the price of Bitcoin from Coinbase.

When these functions are called in a route, you need to check which exchange offers a better price. However, if the if statement that performs this check executes before the functions have finished retrieving the data, you'll run into issues like undefined values. This can lead to errors that can be frustrating to troubleshoot.

The Solution: Using Promises and Async/Await

To tackle this issue effectively, we can utilize Promises and async/await. These tools allow us to manage asynchronous operations more clearly and ensure the order of execution.

Step 1: Refactor to Use Promises

Let's start by modifying the existing functions to return Promises. This will allow the functions to signal when they have finished retrieving data.

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Step 2: Use Async/Await in Your Route Handler

Next, in the route handler where you call these functions, use the async keyword to enable the usage of await, which pauses the execution until the Promise resolves.

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Key Takeaways

Utilize Promises: Wrapping asynchronous calls in Promises lets you handle them more elegantly.

Employ Async/Await: This syntax makes your code cleaner and easier to read. You can write asynchronous code that reads like synchronous code.

Error Handling: Always implement error handling in asynchronous functions to avoid crashes and handle unexpected situations gracefully.

Conclusion

By modifying your functions to return Promises and using async/await in your route handlers, you can ensure that your if statements execute after the necessary data has been retrieved. Keep practicing, and soon you’ll master asynchronous programming in JavaScript!

If you found this article helpful, don’t hesitate to share it with your peers who might be struggling with similar issues! Feel free to leave questions or comments below.

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