function checkNum(data) {      // checks if all characters 
var valid = "0123456789.";     // are valid numbers or a "."
var ok = 1; var checktemp;
for (var i=0; i<data.length; i++) {
checktemp = "" + data.substring(i, i+1);
if (valid.indexOf(checktemp) == "-1") return 0; }
return 1;
}
function dollarAmount(form, field) { // idea by David Turley
Num = "" + eval("document." + form + "." + field + ".value");
dec = Num.indexOf(".");
end = ((dec > -1) ? "" + Num.substring(dec,Num.length) : ".00");
Num = "" + parseInt(Num);
var temp1 = "";
var temp2 = "";
if (checkNum(Num) == 0) {
//alert("This does not appear to be a valid number.  Please try again.");
//focus("document." + form + "." + field);
temp3 = "$0.00";
eval("document." + form + "." + field + ".value = '" + temp3 + "';");
}
else { 
if (end.length == 2) end += "0";
if (end.length == 1) end += "00";
if (end == "") end += ".00";
var count = 0;
for (var k = Num.length-1; k >= 0; k--) {
var oneChar = Num.charAt(k);
if (count == 3) {
temp1 += ",";
temp1 += oneChar;
count = 1;
continue;
}
else {
temp1 += oneChar;
count ++;
}
}
for (var k = temp1.length-1; k >= 0; k--) {
var oneChar = temp1.charAt(k);
temp2 += oneChar;
}
temp2 = "$" + temp2 + end;
eval("document." + form + "." + field + ".value = '" + temp2 + "';");
}
}

function isValidDate(dateStr) {
//var datePat = /^(\d{1,2})(\/|-)(\d{1,2})\2(\d{2}|\d{4})$/;
var datePat = /^(\d{1,2})(\/|-)(\d{1,2})\2(\d{4})$/;
var matchArray = dateStr.match(datePat); // is the format ok?
if (matchArray == null) {
alert("Date is not in a valid format.")
return false;
}
month = matchArray[1]; // parse date into variables
day = matchArray[3];
year = matchArray[4];
if (month < 1 || month > 12) { // check month range
alert("Month must be between 1 and 12.");
return false;
}
if (day < 1 || day > 31) {
alert("Day must be between 1 and 31.");
return false;
}
if ((month==4 || month==6 || month==9 || month==11) && day==31) {
alert("Month "+month+" doesn't have 31 days!")
return false
}
if (month == 2) { // check for february 29th
var isleap = (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0));
if (day>29 || (day==29 && !isleap)) {
alert("February " + year + " doesn't have " + day + " days!");
return false;
}
}
return true;  // date is valid
}