How to set dot(.) at fixed place automatically in javascript? -

please consider highlighted portion in image attached above.

in portion want auto generate dot after add respective digits required in field length field.

i.e.
field :- rate per unit
consider example of field

here want auto generate dot(.) after press 11.

are looking .tofixed(2)?

https://developer.mozilla.org/en-us/docs/javascript/reference/global_objects/number/tofixed