Overcoming undefined Output with Asynchronous Functions in Vue.js

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Imagine you are calling a helper method from your main view like this:

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

To your surprise, the output is:

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

What's happening here? Let’s dive deep into understanding the root of this issue and how to fix it.

Understanding the Asynchronous Nature of Your Helper Function

The core of the problem lies in how asynchronous operations are handled. Let's take a look at your helper function:

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

The Solution: Return a Promise and Use async/await

To resolve this issue, you need to ensure that testMethod1 returns a promise. By doing this, your main view function can wait for the promise to resolve before trying to log the result.

Step 1: Modify the Helper Function

Change your helper function like this:

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

Step 2: Update the Main View Method

Next, update the init method in your main Vue component to handle the asynchronous nature of testMethod1 using async/await:

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

Conclusion: Testing Your Changes

Now, when you call the init method, it will correctly wait for testMethod1() to resolve its promise before logging the result. This should give you the awaited response instead of undefined.

Key Takeaways:

Understand Asynchronous Functions: Asynchronous calls return promises, and direct return from them will typically yield undefined.

Return Promises: Always return the promise from your asynchronous functions.

Use async/await: This allows for cleaner code and proper sequencing of asynchronous calls.