The mod that provide the json (maybe also js) API for Minecraft Modding.
All the definition json should go to the defs folder under your mod assets,
the assets/modid/defs folders.
For Item, it goes items sub-folder: assets/modid/defs/items
For Block, it goes blocks sub-folder: assets/modid/defs/blocks
For Entity, it goes entities sub-folder: assets/modid/defs/entities
All the JSON contained by these 3 folders above, will be loaded into Minecraft.
All the JSON files in definition folder, should be a JSONArray looked like:
[
{component-definition-a},
{component-definition-b}
...
]
Each component definition should have a property id which is unique to others.