Hi,

There are different methods and properties available in CSOM which could be used to get height of grid using java script.

Such properties provide reference of html objects. Using them we can get height. Try with following.

(1)   grid.getDivElement()  (use grid.getDivElement().clientHeight for height)

(2)   grid.DivElement

For further detail check this link: Grid CSOM documentation

Let me know if this helps you.

Greetings