Bug Alert! Update Maps in Angular Signals Requires Careful Handling

When updating a Map stored in an Angular signal, developers may encounter a subtle bug that can lead to incorrect results. The issue arises from how change detection works with object references. When keys are added to the Map, the reference to the original Map remains unchanged, causing Angular's change detection mechanism to fail to recognize updates.

A common mistake is to assume that updating the Map will automatically trigger a recomputation of the signal. However, this assumption can lead to incorrect results and a failure to display updated data in components.

Fortunately, there are several solutions to this bug, including:

1. Overriding the equal function to always return false, which forces the signal to be re-computed.
2. Creating a copy of the Map before updating it, ensuring that the signal receives a new reference and triggers change detection.
3. Storing the Map in an Object and creating a new Object reference after each map operation.

By understanding these potential pitfalls and applying one of these solutions, developers can ensure that their Angular signals accurately reflect changes to their data.

Source: https://dev.to/railsstudent/update-map-in-a-signal-i-wished-someone-told-me-before-i-made-this-mistake-2i39