Question

I need to do user validation of a date field, it should be in the format yyyyMMdd and should not be more than one year in the future. How would I go about doing this? Currently I only have a crude regexp which is insufficient.

function VerifyDate(source, args) {     var regexp = /^([1-2]{1}[0-9]{1})\d{2}([0][1-9]|[1][0-2])([0][1-9]|[1-2][0-9]|[3][0-1])$/     var result = args.Value.match(regexp);          if(result) {         args.IsValid = true;     } else {         args.IsValid = false;     }        } 

Answer 1

Take the regex to check the format only. You can stay simple:

^(\d{4})(\d{2})(\d{2})$ 

Then parse the date and check the range:

function VerifyDate(source, args) {   args.IsValid = false;   var regexp = /^(\d{4})(\d{2})(\d{2})$/;   var daysInMonth = function (y, m) {return 32-new Date(y, m, 32).getDate(); };    var ma = regexp.exec(args.Value);   if (ma && ma.length == 4 && ma[2] < 12 && ma[3] <= daysInMonth(ma[1], ma[2]))   {     var diff = new Date(ma[1], ma[2], ma[3]) - new Date();     args.IsValid = diff < 31536000000; // one year = 1000ms*60*60*24*365   } }