Calculations on fillable forms sometimes not working

Question

     I have a fillable form for a Deposit Slip.  The user enters data about each deposit including the amount and type.   The problem is, if the user of the form randomly clicks on fields to enter data instead of using the Tab to move sequentially from one field to the next; this seems to cause the total fields at the bottom of the form to not correctly sum the data on the form. 
       Is there a way to deal with this?  A way to calculate or re-calculate the form at the end of entry or possibly force the user to Tab through the entire form before the totals appear?

Answer 1

Empty or null fields are assumed to be character strings and not number strings.
The "+" operator in JavaScript is both the addition operative and the concatenation operative. If there is any string value, the computation with the "+" operator becomes a concatenation of strings.
If you are using JavaScript you have to force the empty values to the number format using the "Number" constrictor, the "+" prefix or multipling the field by 1.
event.value =  Number(this.getField("Text1").value) +  (+this.getField("Text2").value) + (1 * this.getField("Text3").value);
The first 2 options for calculations have the above or a similar process to force null strings to zero or to ignore text values.