Validating date format using java script

 // Validates that the input string is a valid date formatted as "mm/dd/yyyy"  
 function isValidDate(dateString)  
 {  
   // First check for the pattern  
   if(!/^\d{1,2}\/\d{1,2}\/\d{4}$/.test(dateString))  
     return false;  
   // Parse the date parts to integers  
   var parts = dateString.split("/");  
   var day = parseInt(parts[1], 10);  
   var month = parseInt(parts[0], 10);  
   var year = parseInt(parts[2], 10);  
   // Check the ranges of month and year  
   if(year < 1000 || year > 3000 || month == 0 || month > 12)  
     return false;  
   var monthLength = [ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ];  
   // Adjust for leap years  
   if(year % 400 == 0 || (year % 100 != 0 && year % 4 == 0))  
     monthLength[1] = 29;  
   // Check the range of the day  
   return day > 0 && day <= monthLength[month - 1];  
 };