Why does Rails precompile essays?

Question

Ruby on Rails

Do I understand correctly that the precompilation of assets by a Rails application is needed in order to "translate" scss code and coffee code into css and js code, respectively?
That is, if I refuse to use coffee scripts and scss markup, then no precompilation will occur?
And one more thing: if there are scripts in both coffee and js formats, will Rails only precompile coffee?
PS How much does precompilation increase page load time? How beneficial is it to use? Is it worth sacrificing page load time for development convenience?

Answer 1

In a development environment, assets are recompiled on-the-fly when the page changes and refreshes.
In a production environment, all your Coffee and SCSS will be minified, compiled, and merged into two static JS and CSS files neatly folded into the public/asssets/ folder

Answer 2

In addition, during the compilation process, a digest will be added to the file name - a hash that guarantees that the user will update the cached assets. Therefore, we must not forget to use image-url and other helpers in Saas files