How to save initial positions from objects into a .json file then load it?

I'm trying to create an level editor, but i need a little help on saving the level as a file, then loading it. How do i save all the positions of the objects into the file? I heard of using the array method, but all the tutorials are a bit hard for me.

See this post, there are links to demo projects:

construct.net/en/forum/construct-2/how-do-i-18/how-to-appear-coins-in-a-spl-p-116804

It's about creating coin patterns, but you can use the same method to add other objects in your level editor.