Javascript's equilvalent of DateDiff Function?

[blakemckenna]

I have a scenario on a web page that compares 2 date fields. When dates are entered their cannot be a difference of more than 365 days. I know VB.Net has the DateDiff() function. I'm pretty new to using Javascript. I've done some searching and couldn't find a DateDiff() function for JS. Was wondering if their is anything like the DateDiff() or does anyone have a homegrown function that will return the difference in dates written in Javascript?

Thanks,

[kows]

What format are your dates in, first of all?

[blakemckenna]

The dates are formatted like this

mm/dd/yyyy or m/d/yyyy

Bottom line is...there has to be a slash and not a . or -

[fjober]

Hello

when we compare between strings we should start from the beginning of them and this requires the date format to be yyyy/mm/dd or (yyyy/m/d), but no problem, in this case and if I were you, I would use the split() function which return your string as an array according to your separator argument:

example:

<script type="text/javascript">
var date1 = "01/23/1992";
var date2 = "11/01/1991";
var compare1 = date1.split("/");
var compare2 = date2.split("/");
// compare1[0] = "01";
// compare1[1] = "23";
// compare1[2] = "1992";
// compare2[0] = "11";
// compare2[1] = "01";
// compare2[2] = "1991";
</script>

as you see we have separated each part of the date so we can compare it easily with another string

Q) what if the day was for example was 1 not 01
A) to solve this problem, when you compare, convert these strings to numbers like this:

<script type="text/javascript">
if (parseInt(compare1[1]) > parseInt(compare2[1])) {
    // the first day is bigger
}
</script>

the parseInt(string, [base]) function parses its first argument, a string, and attempts to return an integer of the specified radix (base).

the last line source is: Core JavaScript reference 1.5

regards

Feras Jobeir

[blakemckenna]

fjober,

I actually ended up doing this. I kinda like the Split function as I use that alot in VB. The parseInt I used exactly the same way your illustrating. That solved the part of my problem that occurred first. Now for the other part and that's a complete Date Validation routine.

Thanks for your input!

[fjober]

When dates are entered their cannot be a difference of more than 365 days

ok sir it is easy, I will do it then replay

[blakemckenna]

Sound good.

Thanks again!

[fjober]

try this function please, return true if the difference is less than a year:

<script type="text/javascript">
    // mm/dd/yyyy
    var validDate = /^\d{1,2}\/\d{1,2}\/\d{4}$/;
    function dateDifference(date1, date2)
    {
        if (validDate.test(date1) && validDate.test(date1)) {
            date1Numbers = date1.split("/");
            date2Numbers = date2.split("/");
            var month1 = date1Numbers[0];
            var month2 = date2Numbers[0];
            var day1 = date1Numbers[1];
            var day2 = date2Numbers[1];
            var yearDif = Math.abs(date1Numbers[2] - date2Numbers[2]);
            if (yearDif <= 1) {
                if (yearDif == 1) {
                    if (month2 <= month1) {
                        if (month2 == month1) {
                            if (day2 <= day1) {
                                calculateDiff(date1Numbers, date2Numbers);
                                return true;
                            } else {
                                return false;
                            }
                        } else {
                            calculateDiff(date1Numbers, date2Numbers);
                        }
                    } else {
                        return false;
                    }   
                } else {
                    calculateDiff(date1Numbers, date2Numbers);
                }
            } else {
                return false;
            }
        } else {
            return false;
        }  
    }
    
    function calculateDiff(date1Numbers, date2Numbers)
    {
        var resultAsDays = 0;
        var day1 = parseInt(date1Numbers[1]);
        var month1 = parseInt(date1Numbers[0]);
        var year1 = parseInt(date1Numbers[2]);
        var day2 = parseInt(date2Numbers[1]);
        var month2 = parseInt(date2Numbers[0]);
        var year2 = parseInt(date2Numbers[2]);
        
        if (year1 == year2) {
            resultAsDays += (Math.abs(month2 - month1)) * 30;
            resultAsDays -= day1;
        } else {
            if (month1 == month2) {
                resultAsDays += 330;
            } else {
                resultAsDays += (12 - (month1 - 1) + month2) * 30;
                resultAsDays -= day1;
            }
        }
        resultAsDays += day2;
        window.alert(resultAsDays);
    }
    </script>

<input type="text" id="date1" />
<input type="text" id="date2" />

<input type="button" value="is valid" onclick="window.alert(dateDifference(document.getElementById('date1').value, document.getElementById('date2').value));" />

hope this to be useful

please try it, I have tested it on some dates and I think it works good

regards

Feras Jobeir