How does Node/V8 determine its max heap size?

I’m looking for a canonical answer here.

How does Node/V8 determine its max heap size?

I’m looking for a canonical answer here.

How does Node/V8 determine its max heap size?

I’m looking for a canonical answer here.

How does Node/V8 determine its max heap size?

I’m looking for a canonical answer here.

In which situation does the node.h library becomes critical over napi.h and other node addon libraries?

I am currently using node.h library to build an addon. It uses, direct v8 type functions to implement. I think, any updates/changes made in v8 functionalites will affect the my addon.