To run code right after page load make a function that checks conditions, for example:
toggleField = ->
if $("#subject_enrolled").val() is "0"
$("#subject_reason_not_enrolled").show()
else
$("#subject_reason_not_enrolled").hide()
return
jQuery ->
$(document).ready ->
/**
* Execute after load
*/
toggleField()
$("#subject_enrolled").on "change", ->
/**
* Execute after change
*/
toggleField()
return
return
return