Date validation with JavaScript

Question

I have a date string in this format - "DD-MM-YYYY" this validates that successfully:

var dateFormat = /(0[1-9]|[12][0-9]|3[01])-(0[1-9]|1[012])-\d{4}/ ;
if(!startDate.match(dateFormat)){
    alert("'Start Date' must be in format: DD-MM-YYYY");
    return false;

I need to check that the inserted date is after today's date(or today's date). how can i do that with JavaScript?

I've tried this: http://www.redips.net/javascript/date-validation/ with the separator, didn't work. suggestions?

Answer 1

Like most I was surprised a what js accepts as the constituent parts of a date. There may be holes in the code below which I would be glad to hear about but this seems to work for me. This assumes a DD/MM/YYYY HH:mm input format.

function strToDate(dtStr) {
                   if (!dtStr) return null
                   let dateParts = dtStr.split("/");
                   let timeParts = dateParts[2].split(" ")[1].split(":");
                   dateParts[2] = dateParts[2].split(" ")[0];
                   // month is 0-based, that's why we need dataParts[1] - 1
                   return dateObject = new Date(+dateParts[2], dateParts[1] - 1, +dateParts[0], timeParts[0], timeParts[1]);
               }
               
// start of validation
var end_time = $('#tbDepartDtTm').val();
end_actual_time = strToDate(end_time);

// convert the date object back to a string in the required format
var dtString = ("0" + end_actual_time.getDate()).slice(-2) + "/" + ("0" + (end_actual_time.getMonth() + 1)).slice(-2) + "/" + end_actual_time.getFullYear() + " " + ("0" + end_actual_time.getHours()).slice(-2) + ":" + ("0" + end_actual_time.getMinutes()).slice(-2);

 if (dtString != end_time) {
      // if the string isn't the same as entered, it must be invalid. msg is a span element.
      msg.textContent = "Depart date is not a valid date.";
      return "Error";
  }

Answer 2

You could do this with moment.js pretty easily.

var input = moment(startDate, "DD-MM-YYYY");
if (input < moment()) {
    // before today
} else {
    // after today
}

We're also adding date validation pretty soon. See more info about validation here: https://github.com/timrwood/moment/pull/306

Answer 3

Thank you all! this did the trick:

var today = new Date();
var Tday = today.getDate();
var Tmonth = today.getMonth()+1; // Zero indexed
var Tyear = today.getFullYear();

var aoDate;
var separator= '-';
aoDate = startDate.split(separator);

var month = aoDate[1] - 0;
    var day = aoDate[0] - 0;
    var year = aoDate[2] - 0;

    if(year < Tyear){
        alert("'Start Date' must be today or after today!");
    return false;
    }
    if((year == Tyear) && (month < Tmonth)){
        alert("'Start Date' must be today or after today!");
    return false;
    }
    if((year == Tyear) && (month == Tmonth) && (day < Tday)){
        alert("'Start Date' must be today or after today!");
    return false;
    }

Answer 4

You should check each date getTime() method and compare it. It's plain and simple, you don't need additional frameworks.

Here is an example that parses the dates from the strings, and then compares them:

var todayDate = "10-05-2012";​ // A sample date
var compareDate1 = "10-05-2012";
var compareDate2 = "03-05-2012";
var compareDate3 = "10-07-2012";

compareDates(todayDate, compareDate1);
compareDates(todayDate, compareDate2);
compareDates(todayDate, compareDate3);

function compareDates(date1String, date2String) {
    var date1 = parseDate(date1String);
    var date2 = parseDate(date2String);
    if(date1.getTime() > date2.getTime()) {
      alert("First date(" + date1String + ") is older than second date(" + date2String + ").");                
    } else if(date1.getTime() < date2.getTime()) {
      alert("First date(" + date1String + ") is younger than second date(" + date2String + ").");                
    } else {
      alert("The dates are the same day");   
    }
}

function parseDate(stringDateParam) {
    var parsedDay = parseInt(stringDateParam.substring(0,2));
    var parsedMonth = parseInt(stringDateParam.substring(3,5))-1;
    var parsedYear = parseInt(stringDateParam.substring(6,10));
    var parsedDate = new Date(parsedYear, parsedMonth, parsedDay, 0 , 0, 0, 0);
    return parsedDate;
}
​

// Output:
//
// First check: The dates are the same day
// Second check: First date(10-05-2012) is older than second date(03-05-2012).
// Third check: First date(10-05-2012) is younger than second date(10-07-2012).

You probably already have a function that parses string to date object, and you should implement a check similar to the one in function compareDates based on getTime() function.

If you have further questions, leave a comment. Good Luck!

JSFiddle working example: click here

Answer 5

First, this is your current date in javascript:

var today = new Date();
var day = today.getDate();
var month = today.getMonth()+1; // Zero indexed

All you need to do, from here, is to compare this with your start date!

Best regards!

check this out maybe it helps to understand the date object.

Answer 6

Check out date.js, specifically...

http://code.google.com/p/datejs/wiki/APIDocumentation#compare

Compares the first date to the second date and returns an number indication of their relative values. -1 = this is < date. 0 = values are equal. 1 = this is > date.

The isAfter() and the isBefore() methods might be useful for your problem :)

Download the library here:

http://code.google.com/p/datejs/downloads/detail?name=date.js&can=2&q=

---

Also, its worth mentioning to checkout moment.js. I think the two libraries complement each other.

Answer 7

Something like this should work. Could use some cleanup, but hopefully gets the point across.

var dateFormat = /(0[1-9]|[12][0-9]|3[01])-(0[1-9]|1[012])-(\d{4})/;
var dateMatch = startDate.exec(dateFormat);
var today = new Date();
today.setHours(0); today.setMinutes(0); today.setSeconds(0); today.setMilliseconds(0);

if ((new Date(dateMatch[3], dateMatch[2] - 1, dateMatch[1])).getTime() >= today.getTime()) {
    // Date is after or on today
}