Check the Date

The below script provides to how to check the entered date is the correct date or not like by selecting the april if we select 31 days it has to prompt the entered date is the invalid date. Such type of scenarios can be tested with the below javascript.

var mth = new Array(' ','january','february','march','april','may','june','july','august','september','october','november','december');
var day = new Array(31,28,31,30,31,30,31,31,30,31,30,31);

function validateDate(fld,fmt,rng) {
var dd, mm, yy;var today = new Date;var t = new Date;fld = stripBlanks(fld);
if (fld == '') return false;var d1 = fld.split('\/');
if (d1.length != 3) d1 = fld.split(' ');
if (d1.length != 3) return false;
if (fmt == 'u' || fmt == 'U') {
dd = d1[1]; mm = d1[0]; yy = d1[2];
}
else if (fmt == 'j' || fmt == 'J') {
dd = d1[2]; mm = d1[1]; yy = d1[0];
}
else if (fmt == 'w' || fmt == 'W'){
dd = d1[0]; mm = d1[1]; yy = d1[2];
}
else return false;
var n = dd.lastIndexOf('st');
if (n > -1) dd = dd.substr(0,n);
n = dd.lastIndexOf('nd');
if (n > -1) dd = dd.substr(0,n);
n = dd.lastIndexOf('rd');
if (n > -1) dd = dd.substr(0,n);
n = dd.lastIndexOf('th');
if (n > -1) dd = dd.substr(0,n);
n = dd.lastIndexOf(',');
if (n > -1) dd = dd.substr(0,n);
n = mm.lastIndexOf(',');
if (n > -1) mm = mm.substr(0,n);
if (!isNumber(dd)) return false;
if (!isNumber(yy)) return false;
if (!isNumber(mm)) {
var nn = mm.toLowerCase();
for (var i=1; i < 13; i++) {
if (nn == mth[i] ||
nn == mth[i].substr(0,3)) {
mm = i; i = 13;
}
}
}
if (!isNumber(mm)) return false;
dd = parseFloat(dd); mm = parseFloat(mm); yy = parseFloat(yy);
if (yy < 100) yy += 2000;
if (yy < 1582 || yy > 4881) return false;
if (mm == 2 && (yy%400 == 0 || (yy%4 == 0 && yy%100 != 0))) day[mm-1]++;
if (mm < 1 || mm > 12) return false;
if (dd < 1 || dd > day[mm-1]) return false;
t.setDate(dd); t.setMonth(mm-1); t.setFullYear(yy);
if (rng == 'p' || rng == 'P') {
if (t > today) return false;
}
else if (rng == 'f' || rng == 'F') {
if (t < today) return false;
}
else if (rng != 'a' && rng != 'A') return false;
return true;