RosettaCodeData/Task/Date-manipulation/JavaScript/date-manipulation.js

42 lines
1.4 KiB
JavaScript

function add12hours(dateString) {
// Get the parts of the date string
var parts = dateString.split(/\s+/),
date = parts[1],
month = parts[0],
year = parts[2],
time = parts[3];
var hr = Number(time.split(':')[0]),
min = Number(time.split(':')[1].replace(/\D/g,'')),
ampm = time && time.match(/[a-z]+$/i)[0],
zone = parts[4].toUpperCase();
var months = ['January','February','March','April','May','June',
'July','August','September','October','November','December'];
var zones = {'EST': 300, 'AEST': -600}; // Minutes to add to zone time to get UTC
// Convert month name to number, zero indexed. Return if invalid month
month = months.indexOf(month);
if (month === -1) { return; }
// Add 12 hours as specified. Add another 12 if pm for 24hr time
hr += (ampm.toLowerCase() === 'pm') ? 24 : 12
// Create a date object in local zone
var localTime = new Date(year, month, date);
localTime.setHours(hr, min, 0, 0);
// Adjust localTime minutes for the time zones so it is now a local date
// representing the same moment as the source date plus 12 hours
localTime.setMinutes(localTime.getMinutes() + zones[zone] - localTime.getTimezoneOffset() );
return localTime;
}
var inputDateString = 'March 7 2009 7:30pm EST';
console.log(
'Input: ' + inputDateString + '\n' +
'+12hrs in local time: ' + add12hours(inputDateString)
);