Solve the vue3 Composition API Array Replacement Rerendering Issue with Ease

Discover how to effectively replace arrays in Vue 3 Composition API without rendering issues. Learn key techniques and solutions to optimize your component's performance.
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Dealing with Array Replacement in Vue 3 Composition API

When working with arrays in Vue 3's Composition API, developers may find themselves facing some peculiar challenges, especially regarding how and when the view updates based on array manipulations. In this guide, we will explore a common issue of failing to rerender a Vue component when replacing a ref array with a new one.

The Problem

You might encounter a situation where you intend to replace a ref<number[]> array (list2) with a new, non-ref array (listNoRef). Upon performing the replacement, you notice that the associated Vue component does not rerender, even though the console shows that the new values are, indeed, being assigned correctly.

Here’s a simplified example:

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

In this scenario, you can see logs that confirm the new values are set, but the UI doesn’t reflect these changes as expected. Interestingly, if another event triggers rerendering, the list appears updated, meaning that the data isn't lost, but the UI binding is not catching the change.

The Root Cause

This issue arises because simply assigning a new array reference does not force Vue’s reactivity system to trigger updates to the view. Vue relies on its reactivity tracking system and does not see the assignment to a ref value as a mutation that requires updates.

Solution: Copying the Array by Value

To effectively replace your array and properly trigger Vue’s rerendering mechanism, you can copy the array by value instead of merely reassigning the reference. By using the spread syntax, you can achieve this functionality like so:

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

This creates a new array based on listNoRef, allowing Vue’s reactivity system to recognize the change and update the UI accordingly.

Updated Implementation

Let's look at an updated implementation of the addAnswer2 function that utilizes this approach:

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

Complete Code Example

Below is a complete example of how your Vue component might look after implementing this solution:

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

Conclusion

Managing reactivity in Vue 3's Composition API can sometimes be tricky, especially with array replacements. The best practice to ensure your UI updates correctly is to utilize methods that create a new reference to the data structure you are working with. In this case, utilizing the spread operator allows you to effectively manage and present your array of data without running into rerendering issues.

By following this guidance, you can enhance the performance of your Vue application and create a smoother user experience.