How can you control the download of scripts for mobile phones?

Question

JavaScript

What is available:
backend from nodejs + expressjs
I would like not to download certain scripts for mobile phones.
how to solve the problem at the moment.
Do not insert scripts with the help of the backend on the condition or in the frontend body.append on the condition?

Answer 1

On one of the projects I solved a similar problem as follows.
Grunt builds 2 or more sets - scripts+styles.
Further, during rendering, the user agent and other parameters are determined and the required set of plug-in scripts is substituted.

Answer 2

On the backend, giving different URLs to the same URL depending on the device is not correct. You need to decide on the frontend to load one or another minified and compressed js package. Take a loader, for example: requirejs.org