How to make help text display conditionally

[nicolemccray]

I have an 'onLoad' script that will make the help text always visible.   But instead, I need an onChange script that will display it conditionally.   If 'designate_proxy' field = yes, the help text should expand:

How can I modify the script for this to work?:

    var myVar = g_form.getControl('designate_proxy');

    toggleHelp(myVar.id);

[nicolemccray]

Tried this code, and now the text does not display at all:

function onChange(control, oldValue, newValue, isLoading) {
    if (isLoading || newValue == '') {
          return;
    }

    //Type appropriate comment here, and begin script below
var val =g_form.getvalue('designate_proxy');
if(val == 'Yes'){

var elems = document.getElementsByClassName('sc-help-text annotation-wrapper');
  for (var i=0;i<elems.length;i+=1){

  if (elems[i].style.display === 'none') {
  elems[i].style.display = 'block';
  }


}
  }
if(val == 'No'){

var elem = document.getElementsByClassName('sc-help-text annotation-wrapper');
  for (var i=0;i<elem .length;i+=1){

  if (elem [i].style.display === 'none') {
  elem[i].style.display = 'none';
  }


}
}
}