Set the unit values in milliseconds. Set a date and get the milliseconds Set the date to January 1, at midnight, of the specified year.

// Set the unit values in milliseconds.
var msecPerMinute = 1000 * 60;
var msecPerHour = msecPerMinute * 60;
var msecPerDay = msecPerHour * 24;

// Set a date and get the milliseconds
var date = new Date('6/15/1990');
dateMsec = date.getTime();

// Set the date to January 1, at midnight, of the specified year.
date.setMonth(0);
date.setDate(1);
date.setHours(0, 0, 0, 0);

// Get the difference in milliseconds.
var interval = dateMsec - date.getTime();

// Calculate how many days the interval contains. Subtract that
// many days from the interval to determine the remainder.
var days = Math.floor(interval / msecPerDay );
interval = interval - (days * msecPerDay );

// Calculate the hours, minutes, and seconds.
var hours = Math.floor(interval / msecPerHour );
interval = interval - (hours * msecPerHour );

var minutes = Math.floor(interval / msecPerMinute );
interval = interval - (minutes * msecPerMinute );

var seconds = Math.floor(interval / 1000 );

// Display the result.
document.write(days + " days, " + hours + " hours, " + minutes + " minutes, " + seconds + " seconds.");

//Output: 164 days, 23 hours, 0 minutes, 0 seconds.
(3:28 PM) Naveen M: // Set the unit values in milliseconds.
var msecPerMinute = 1000 * 60;
var msecPerHour = msecPerMinute * 60;
var msecPerDay = msecPerHour * 24;

// Set a date and get the milliseconds
var date = new Date('6/15/1990');
dateMsec = date.getTime();

// Set the date to January 1, at midnight, of the specified year.
date.setMonth(0);
date.setDate(1);
date.setHours(0, 0, 0, 0);

// Get the difference in milliseconds.
var interval = dateMsec - date.getTime();

// Calculate how many days the interval contains. Subtract that
// many days from the interval to determine the remainder.
var days = Math.floor(interval / msecPerDay );
interval = interval - (days * msecPerDay );

// Calculate the hours, minutes, and seconds.
var hours = Math.floor(interval / msecPerHour );
interval = interval - (hours * msecPerHour );

var minutes = Math.floor(interval / msecPerMinute );
interval = interval - (minutes * msecPerMinute );

var seconds = Math.floor(interval / 1000 );

// Display the result.
document.write(days + " days, " + hours + " hours, " + minutes + " minutes, " + seconds + " seconds.");

//Output: 164 days, 23 hours, 0 minutes, 0 seconds.