Show or hide subform based on dropdown selection using javascript

Hello,

Need help on javascript.

Could someone please help me convert the below Form calc code into Javascript code
-> for Exit event  of dropdown field ‘Positiongrade’
-> that has YES and NO values

-> to hide/visible the2 subforms ‘jobraising’ and ‘posforprom’ based on below FormCalc condition

if(data.Bodysubform.Promsel. Positiongrade == "Yes")  

then

data.Bodysubform.jobraising.presence = "visible"

  data.Bodysubform.posforprom.presence = "hidden"

endif

if(data.Bodysubform.Promsel. Positiongrade == "No")

then

data.Bodysubform.posforprom.presence = "visible"

data.Bodysubform.jobraising.presence = "hidden"

endif

I tested above FormCalc code and it works in other forms.

I cannot use the FormCalc script for this event because I already have generated code in javascipt which should not be modified.
So I need to use Javascript in this form.

Thanks much!