JavaScript: Calculator Script - DATE DIFFERENCE CALCULATOR

Main Calculator Script DATE DIFFERENCE CALCULATOR

<!-- TWO STEPS TO INSTALL DATE DIFFERENCE:

1.  Copy this part of code inside your HTML HEAD

2.  Add the last code into the BODY of your HTML document  -->

<HEAD><title>JavaScript, java script, javascripts, script, javascript free code!</title>

<!-- Begin

function isValidDate(dateStr) {

// Date validation function courtesty of

// Sandeep V. Tamhankar (stamhankar@hotmail.com) -->

// Checks for the following valid date formats:

// MM/DD/YY   MM/DD/YYYY   MM-DD-YY   MM-DD-YYYY

var datePat = /^(\d{1,2})(\/|-)(\d{1,2})\2(\d{4})$/; // requires 4 digit year

var matchArray = dateStr.match(datePat); // is the format ok?

if (matchArray == null) {

alert(dateStr + " Date is not in a valid format.")

return false;

}

month = matchArray[1]; // parse date into variables

day = matchArray[3];

year = matchArray[4];

if (month < 1 || month > 12) { // check month range

alert("Month must be between 1 and 12.");

return false;

}

if (day < 1 || day > 31) {

alert("Day must be between 1 and 31.");

return false;

}

if ((month==4 || month==6 || month==9 || month==11) && day==31) {

alert("Month "+month+" doesn't have 31 days!")

return false;

}

if (month == 2) { // check for february 29th

var isleap = (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0));

if (day>29 || (day==29 && !isleap)) {

alert("February " + year + " doesn't have " + day + " days!");

return false;

}

return true;

}

function isValidTime(timeStr) {

// Time validation function courtesty of

// Sandeep V. Tamhankar (stamhankar@hotmail.com) -->

// Checks if time is in HH:MM:SS AM/PM format.

// The seconds and AM/PM are optional.

var timePat = /^(\d{1,2}):(\d{2})(:(\d{2}))?(\s?(AM|am|PM|pm))?$/;

var matchArray = timeStr.match(timePat);

if (matchArray == null) {

alert("Time is not in a valid format.");

return false;

}

hour = matchArray[1];

minute = matchArray[2];

second = matchArray[4];

ampm = matchArray[6];

if (second=="") { second = null; }

if (ampm=="") { ampm = null }

if (hour < 0  || hour > 23) {

alert("Hour must be between 1 and 12. (or 0 and 23 for military time)");

return false;

}

if (hour <= 12 && ampm == null) {

if (confirm("Please indicate which time format you are using.  OK = Standard Time, CANCEL = Military Time")) {

alert("You must specify AM or PM.");

return false;

}

if  (hour > 12 && ampm != null) {

alert("You can't specify AM or PM for military time.");

return false;

}

if (minute < 0 || minute > 59) {

alert ("Minute must be between 0 and 59.");

return false;

}

if (second != null && (second < 0 || second > 59)) {

alert ("Second must be between 0 and 59.");

return false;

}

return true;

}

function dateDiff(dateform) {

date1 = new Date();

date2 = new Date();

diff  = new Date();

if (isValidDate(dateform.firstdate.value) && isValidTime(dateform.firsttime.value)) { // Validates first date

date1temp = new Date(dateform.firstdate.value + " " + dateform.firsttime.value);

date1.setTime(date1temp.getTime());

}

else return false; // otherwise exits

if (isValidDate(dateform.seconddate.value) && isValidTime(dateform.secondtime.value)) { // Validates second date

date2temp = new Date(dateform.seconddate.value + " " + dateform.secondtime.value);

date2.setTime(date2temp.getTime());

}

else return false; // otherwise exits

// sets difference date to difference of first date and second date

diff.setTime(Math.abs(date1.getTime() - date2.getTime()));

timediff = diff.getTime();

weeks = Math.floor(timediff / (1000 * 60 * 60 * 24 * 7));

timediff -= weeks * (1000 * 60 * 60 * 24 * 7);

days = Math.floor(timediff / (1000 * 60 * 60 * 24));

timediff -= days * (1000 * 60 * 60 * 24);

hours = Math.floor(timediff / (1000 * 60 * 60));

timediff -= hours * (1000 * 60 * 60);

mins = Math.floor(timediff / (1000 * 60));

timediff -= mins * (1000 * 60);

secs = Math.floor(timediff / 1000);

timediff -= secs * 1000;

dateform.difference.value = weeks + " weeks, " + days + " days, " + hours + " hours, " + mins + " minutes, and " + secs + " seconds";

return false; // form should never submit, returns false

}

//  End -->

</script>

</HEAD>

<BODY>

<table>

<pre>

First Date:   Date: <input type=text name=firstdate value="" size=10 maxlength=10>  (MM/DD/YYYY format)

Time: <input type=text name=firsttime value="" size=10 maxlength=10>  (HH:MM:SS format)

Second Date:  Date: <input type=text name=seconddate value="" size=10 maxlength=10>  (MM/DD/YYYY format)

Time: <input type=text name=secondtime value="" size=10 maxlength=10>  (HH:MM:SS format)

Date Difference:<br>

</center>

</pre>

</td></tr>

</table>

</form>

</center>

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