// Date Validation and Format Javascript
// copyright 11th June 2007 by Stephen Chapman
// permission to use this Javascript on your web page is granted
// provided that all of the code in this script (including these
// comments) is used without any alteration
// you may swap the 12 and 31 around if you want mm/dd instead of dd/mm
// WARNING: ADD THE FOLLOWING DIRECTLY TO THE FIELD YOU WANT THIS TO WORK ON    onkeyup="dtval(this,event)"

function dtval(d,e) {
var pK = e ? e.which : window.event.keyCode;
if (pK == 8) {d.value = substr(0,d.value.length-1); return;}
var dt = d.value;
var da = dt.split('/');
for (var a = 0; a < da.length; a++) {if (da[a] != +da[a]) da[a] = da[a].substr(0,da[a].length-1);}
if (da[0] > 31) {da[1] = da[0].substr(da[0].length-1,1);da[0] = '0'+da[0].substr(0,da[0].length-1);}
if (da[1] > 12) {da[2] = da[1].substr(da[1].length-1,1);da[1] = '0'+da[1].substr(0,da[1].length-1);}
if (da[2] > 9999) da[1] = da[2].substr(0,da[2].length-1);
dt = da.join('/');
if (dt.length == 2 || dt.length == 5) dt += '/';
d.value = dt;
}