Validate Date and block JavaScript page change

Question

how I can validate date acrobat, can block JavaScript page change, only change with a button? 

Answer 1

If you use the "util.scand" method date validation is part of the process. It either returns the number of milliseconds from the Epoch date used by JavaScript for the date time object the null value.
Date Arithmetic has some sample scripts, but you need to keep in mind that Date and Time are not independent and using "new Date()" returns the date and time at the time that line of code is executed and that can cause issues for the computing of dates only.
Are you sure of day count, most differences include the start and end dates in the number of days for the calculation.
Custom calculation for today's date field (format is None):
// get today's date an time
var oToday = new Date();
// set to start of day
oToday.setFullYear(oToday.getFullYear(), oToday.getMonth(), oToday.getDate(), 0, 0, 0, 0)
// set field value
event.value = util.printd("d/mm/yyyy", oToday);
Custom calculation for the difference in days field (format None):
var cEnteredDate = this.getField("EnteredDate").value;
var cToday = this.getField("Today").value;
event.value = "";
if(cEnteredDate != "" && cToday != "") {
// process only if date values not empty
// convert date strings to date time objectat midnight
var oEnteredDate = util.scand("d/mm/yyyy", cEnteredDate );
if (oEnteredDate == null) {
app.alert("Error in processing entered date", 2, 0);
oEnteredDate.setFullYear(oEnteredDate.getFullYear(), oEnteredDate.getMonth(),oEnteredDate.getDate(), 0, 0, 0, 0) 
var oToday = util.scand("d/mm/yyyy", cToday);
if(oToday ==  null) {
app.alert("Error converting today", 2,0);
oToday.setFullYear(oToday.getFullYear(), oToday.getMonth(),oToday.getDate(), 0, 0, 0, 0) 
// convert date objects to days
var nEnteredDate = Math.floor(oEnteredDate.getTime() / (1000 * 60 * 60 * 24));
var nToday = Math.floor(oToday.getTime() / (1000 * 60 * 60 * 24));
// compute & format the difference
event.value = util.printf("%,0 1.0f", (nToday - nEnteredDate));