JavaScript check date format function [Compare full]_ time Date

text box name for date = "Indate"
function Check1 (Form)
{
for (i = 0; i < form.length; i++)
{
if (Form.elements[i].value = "")
{
Alert ("Please complete!")
Form.elements[i].focus ();
Return
}

if (Form.elements[i].name = = "Indate")
{
var date = Form.elements[i].value;
len = date.length;
var Datearray = Date.split ("-")
Alert (datearray[1]);
var year = parseint (datearray[0]);
var month = parseint (datearray[1]);
var day = parseint (datearray[2]);

if (len = = "")
{
Alert ("Time cannot be empty");
Return
}
else if (Len > 10)
{
Alert ("Incorrect date format");
Return
}
else if (isNaN (year))
{
Alert ("Incorrect date format");
Return
}
else if (Year > 9999) | | (Year < 100))
{
Alert ("Incorrect date format");
Return
}
else if (isNaN (month))
{
Alert ("Incorrect date format");
Return
}
else if ((Month > 12) | | (Month < 1))
{
Alert ("Incorrect date format");
Return
}
else if (isNaN (day))
{
Alert ("Incorrect date format");
Return
}
Else
{
Switch (month)
{
Case 1:
Case 3:
Case 5:
Case 7:
Case 8:
Case 10:
Case 12:
if ((Dat < 0) | | (Day > 31))
{
Alert ("Incorrect date format");
Return
}
Break
Case 4:
Case 6:
Case 9:
Case 11:
if (Day < 0) | | (Day > 30))
{
Alert ("Incorrect date format");
Return
}
Break
Default
if (year% = 0) && (year% 4 = 0))
{
if (Day < 0) | | (Day > 29))
{
Alert ("Incorrect date format");
Return
}
}
Else
{
if (Day < 0) | | (Day > 28))
{
Alert ("Incorrect date format");
Return
}
}
}
}
}
}
Form.submit ();
}