Showing negative numbers as 0

Question

Box 1: User Input
Box 2: User Input
Box 3: User Input
Box 4: User Input
Box 5: (Box 1 - Box 2)
Box 6: (Box 3 + Box 4)
Box 7: (Box 5 - Box 6)
So I'm using the following equation for Boxes 5, 6 & 7:
var v1 = getField("Box #").valueAsString;
var v2 = getField("Box #").valueAsString;
     if (v1 && v2) {
        // Perform the calculation
        event.value = +v1 - +v2;
     } else {
         event.value = "";
**Note for box 6, the in the calculation is replaced with (+).
My question: How do I write this code to produce/show "0" if the equation results in a negative number?

Answer 1

You need another "if" statement or you use a logical value to multiply the result of the calculation by 1 if not negative or by 0 if negative. The logical true and false have a numerical value. True is 1 and false is 0,
var v1 = this.getField("Box #").valueAsString;
var v2 = this.getField("Box #").valueAsString;
event.value = "";
      if (v1 && v2) {
        // Perform the calculation
        if((v1 - 2) >= 0)  event.value = (v1 - 2) * ((v1 - 2) >= 0); // display result for non-negative values;
        else event.value = 0; // display 0 for negative values;
or:
var v1 = this.getField("Box #").valueAsString;
var v2 = this.getField("Box #").valueAsString;
event.value = "";
if (v1 && v2) {
       // Perform the calculation;
     // display result if not negative or 0;
        event.value = (v1 - 2) * ((v1 - 2) > 0);
Since the calculation is repeated with only a change in the field names, I would consider using a function that takes the field names as parameters and returns the result of the calculation.
// document level or page open function;
function PosativeResult(cField1, cField2, cOper) {
var v1 = this.getField(cField1).valueAsString;
var v2 = this.getField(cField2).valueAsString;
if(typeof cOper == "undefined") cOper = "+";
var nResult = "";
if (v1 && v2) {
       // Perform the calculation;
        nResult = eval(Number(v1) + " " + cOper + " " + Number(v2))
          // display only positive results or zero;
        nResult *= (nResult > 0);
return nResult;
} // end PosaiveResult function;
// custom calculation for Box5;
event.value = PosativeResult("Box1", "Box2", "-");
// custom calculation for Box6;'
event.value = PosativeResult("Box3", "Box4", "+");
// custom calculation for Box7;
event.value = PosativeResult("Box5", "Box6", "-");
Are you sure you provided the correct equations for the field values?
Changing the operator make the script more complex.