How to Re-center React Google Maps on Adding a Marker

Discover the solution to recentering a Google Map in your React application when a new marker is added, using the @ react-google-maps/api library.
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This video is based on the question https://stackoverflow.com/q/70931285/ asked by the user 'U. Watt' ( https://stackoverflow.com/u/8845766/ ) and on the answer https://stackoverflow.com/a/70934765/ provided by the user 'Justin Poehnelt' ( https://stackoverflow.com/u/3145360/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Re-center React Google Maps on Adding a Marker

Working with Google Maps in a React application can be a bit tricky, especially when it comes to dynamically updating the map view. If you're using the @ react-google-maps/api library and want to re-center your map every time you add a new marker, you’re in the right place. Many developers encounter issues getting the map to adjust appropriately as they add or remove markers, and this guide will guide you through troubleshooting and implementing a proper solution.

The Problem

Imagine you've implemented a map in your application displaying various markers. Now, you want to add a new marker upon the click of a button and automatically adjust the map so that all markers are visible. However, you might run into an error that reads:

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

This is frustrating, but it typically means that you're trying to access the Google Maps API before it has fully loaded.

Understanding the Cause of the Error

The root of the issue lies in when the Google Maps API is ready for use. If your useEffect to set the bounds for the map runs before the API is fully loaded, it throws an error because the window.google.maps property doesn’t exist yet. Here's a breakdown of why this happens:

State Initialization: Your map variable is initialized to undefined and only gets the value once the GoogleMap component has been loaded.

Timing is Everything: If your effect runs before the map state is populated, the window.google.maps object doesn't exist, leading to the error when you try to create new LatLngBounds().

Step-by-Step Solution

To avoid this error, you'll want to make sure your map state is set before you try to adjust the bounds. Here’s how to properly structure your useEffect to take this into account:

Step 1: Check if the Map is Defined

Before creating bounds and trying to fit them, check if the map is loaded correctly. This ensures that you only attempt to adjust the map when you have access to the API.

Step 2: Update the useEffect

Modify your useEffect as follows:

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

Breakdown of the Code

The conditional check (if (map)) ensures that you only attempt to create bounds if the map instance is available.

It loops through the existing markers, extending the bounds for each marker’s latitude and longitude.

Finally, it adjusts the map’s view to fit the bounds, ensuring all markers are visible.

Running Your Code

After updating your useEffect, run your component again. You should now see that when you add new markers, the map properly re-centers to show all of them without throwing errors.

Conclusion

Implementing dynamic charts or maps in a React application can present challenges, but with proper state management and checks, you can effectively solve these issues. By ensuring that the Google Maps API is loaded before attempting to access its properties, you can circumvent common pitfalls that lead to runtime errors.

Next time you find yourself needing to dynamically adjust your Google Map, remember this pattern, and your implementation should run smoothly. Happy mapping!