You are correct about the fact that all front-end code is always visible to the end user.
I think the recommended method the author is referring to is a .env like file (npmjs.com/package/dotenv). Which does not hide the values but makes them more variable and easier to change without having to alter your code.
You might want your front-end connecting to different base URL's depending on what environment it is running (dev, staging, prod).
You are correct about the fact that all front-end code is always visible to the end user.
I think the recommended method the author is referring to is a .env like file (npmjs.com/package/dotenv). Which does not hide the values but makes them more variable and easier to change without having to alter your code.
You might want your front-end connecting to different base URL's depending on what environment it is running (dev, staging, prod).
Thanks for the response. Your points make sense.