How to run this craft.js code on localhost or local pc

[a-sh-i-sh]

How to run this craft.js code run after cloning in laptop, which command are helpful to run this code on localhost ?
If you know please explain its running step ... and may be possible what the reason of use package.json file inside its folder because if we make a project its have only one package.json file which tell about which packages we need to install ?