Making dependent field required if data entered in trigger field, but NOT if trigger data deleted

Hello.  I have a form where the trigger field is A.  The dependent fields are 1 and 2 (just for simplicity's sake).  If the user enters data in A, 1 and 2 become required.  BUT, if the user deletes the data in A, 1 & 2 REMAIN required.  How do I script 1 & 2 becoming "unrequired" if A becomes blank after data was previously entered in field A?  I have this script so far:

var A = this.getField("A").value;

if(A="")

{

this.getField("1").required = false;

this.getField("2").required = false; }else

{

this.getField("1").required = true;

this.getField("2").required = true; }