Third option to allow text box to be fully editable.

[Hoey]

I would like to apologize in advance if this question has been asked before. I believe that my wording isn't the best for this issue.

So I have a dropdown with some choices. All of those choices have a calcuation one way or another. Only 2 options for the calculation. 

if (this.getField("insuranceDD").value == 0) {
    event.value = ((this.getField("projectCostFull").value * .65) - this.getField("splitDed").value).toFixed(2);
} else {
    event.value = ((this.getField("projectCostFull").value * .50) - this.getField("splitDed").value).toFixed(2);
}

I would like to know is if there is a way that I can add a 3rd option that would allow the text box that this javascript is in to be fully editable. I know I will have to add an else if to allow a 3rd option and I thought using:

else {
   event.value = ""
}

but that just locks up the text box not allowing it to be editable. Also, the formatting for the text box is for currency if that matters. 

I appreciate any/all help and thank you in advance! 

[try67 · Accepted solution]

Sure. Just don't set event.value ...

[Hoey]

Dang it! I was close! As always, thank you for you help @try67 it is always appreciated! 

[Hoey]

I'm sorry @try67, one more question. What would I put in place of event.value? 

[try67]

Nothing... Just drop the last else clause entirely.