Script to list dropdown responses

I have a questionaire with drop down boxes with Y or N  option for each question

Looking to produce CSV text Y =1 N=O to list responses once selected 

trying this below but doesnt work as intended. Any help would be appreciated. 

event.value = "";
var a = this.getField("dropdown1").value;

if(a != "Y"){
event.value = "1, ";
}

else if(a != "N"){
event.value = "0, ";
}
var b = this.getField("dropdown2").value;

if(b != "Y"){
event.value += "1, ";
}
else if(b != "N"){
event.value = "0, ";
}