Introduction
Are you building your first mobile application using React Native? If you’re facing the “React Native Undefined is not a function” error with the error message pointing to the ‘…data.map(…)’ line in your code, don’t worry! In this article, we’ll dive into the issue and guide you through the troubleshooting process to get your application working flawlessly. Let’s get started!
Understanding the Error
When attempting to test your React Native code on your phone, encountering the “React Native Undefined is not a function” error can be frustrating. This error specifically points to the ‘…data.map(…)’ line in your code. Let’s understand why this error occurs and how we can resolve it.
The Root Cause
The primary reason behind this error is that the response from your API call does not return an array, but an object instead. Consequently, the ‘data’ variable becomes an object, and when you try to use the map function on an object, the error occurs. Now, let’s explore the solutions to fix this issue and get your markers to display correctly.
Adjusting the Code
To resolve the “React Native Undefined is not a function” error, follow these steps:
- Open the ‘mapMarker.js’ file in your React Native project.
- Locate the API fetch code block where you’re fetching the data.
- Within the fetch
.then()block, modify the code as follows:
code
.then(response => response.json())
.then(results => {
setData(results.details); // Change 'results' to 'results.details'
console.log(results);
})
.catch(error => console.error(error));
By updating the code to setData(results.details), you ensure that the ‘data’ variable receives the array of details returned by the API instead of the entire response object.
Verifying the Changes
After applying the code adjustments, you should observe the following:
- The “React Native Undefined is not a function” error should no longer appear.
- The console should log the expected results.
- The markers should be displayed correctly on the map in your mobile application.
Conclusion
Congratulations! You’ve successfully resolved the “React Native Undefined is not a function” error by adjusting the code to properly handle the response from the API. By following the steps outlined in this article, you can overcome this error and ensure your React Native mobile application functions as intended. Keep coding and building amazing applications!
Remember, encountering errors and troubleshooting them is a vital part of the learning process for any developer. Embrace these challenges as opportunities to expand your skills and understanding.
If you found this article helpful, feel free to share it with other developers who might be facing similar issues.
