NOTE: I don't know if this works on windows. Installing the bash shell on windows 10 is possible, but I did not test if this script works there.
For a tutorial on how to install bash on windows, click here.

This is a handy little script that allows you to get the default Minecraft assets quickly. It is very easy to use:
1. Run the script in a terminal
2. If you want, enter V or v to select a version
Before you extract, make sure there is no folder with the name 'out' in the directory you are running the script in.
3. Enter S or s to start extracting.
After a few seconds, you should have a folder named 'out' in your directory. This is the folder that contains all your extracted assets.
Enjoy!
NOTE: This script does NOT extract the sounds, as they are not inside the minecraft.jar file.

btw I uploaded the ZIP file on Google Drive because PMC did not accept the file.