Need help making digital signature field read only if required fields are null

Question

Using Adobe LiveCycle Designer, I have a digital signature field.  I want to prevent users from being able to digitally sign the pdf if any required fields in the pdf are null or blank.  I'm a newbie to scripting so any detailed help would be greatly appreciated.  The required fields in the pdf include radio buttons, check boxes, text field, etc.  I appreciate any help anyone can provide.
Thanks

Answer 1

Exactly how you check a field for being empty depends on what type of field it is. For text fields, you should get the field's value as a string and compare it to an empty string, something like:
var val = getField("Text1").valueAsString;
if (val) {
    app.alert("Field is not empty");
If there is a default value that needs to be changed, you would compare to the default value:
var f = getField("Text1");
var val = f.valueAsString;
if (val !== f.defaultValue) {
    app.alert("Field value is OK");
For check boxes and radio buttons, you'd compare to the string "Off", which means none in the group is selected.
For dropdowns (combo boxes) and list boxes, there is normally one value selected, so you would have to get the value and check against the default value (or something else) to see if the field is properly filled in.
You could place the script there, but I usually use a separate button that I encourage the user to click in order to check the field. The problem with using the Will Save event is you can't prevent the save from happening.
The script can loop through all of the fields (and test all required ones), or you could set up an array of field names to check.