How to programmatically set the language in a React app? 

When building a React app with localization requirements, it's important to ensure that the user's preferred language is reflected in the app's language settings. This can be done programmatically by setting up a state variable that tracks the user's preferred language, and then using a localization library to handle the display of localized messages in the app.

The specific implementation will depend on the localization library being used. For example, some libraries may have their own methods for setting the language, while others may require you to update the state variable manually and then trigger a re-render of the app.

Here's an example of how you can programmatically set the language in a React app that utilizes the react-intl library for localization.