52 lines
1.5 KiB
JavaScript
52 lines
1.5 KiB
JavaScript
function add12hours(dateString) {
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// Get the parts of the date string
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var parts = dateString.split(/\s+/);
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var date = parts[1];
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var month = parts[0];
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var year = parts[2];
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var time = parts[3];
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var ampm = time && time.match(/[a-z]+$/i)[0];
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var hr = Number(time.split(':')[0]);
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var min = Number(time.split(':')[1].replace(/\D/g,''));
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var zone = parts[4].toUpperCase();
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var months = ['January','February','March','April','May','June',
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'July','August','September','October','November','December'];
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var zones = {'EST': 300, 'AEST': -600}; // Minutes to add to zone time to get UTC
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// Convert month name to number, zero indexed
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// Could use indexOf but not supported widely
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for (var i=0, iLen=months.length; i<iLen; i++) {
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if (months[i] == month) {
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month = i;
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}
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}
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if (typeof month != 'number') return; // Invalid month name provided
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// Convert hours to 24hr
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if (ampm && ampm.toLowerCase() == 'pm') {
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hr += 12;
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}
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// Add 12 hours to hours
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hr += 12;
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// Create a date object in local zone
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var d = new Date(year, month, date);
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d.setHours(hr, min, 0, 0);
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// Adjust minutes for the time zones
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d.setMinutes(d.getMinutes() + zones[zone] - d.getTimezoneOffset() );
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// d is now a local date representing the same moment as the
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// source date plus 12 hours
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return d;
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}
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var inputDateString = 'March 7 2009 7:30pm EST';
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alert(
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'Input: ' + inputDateString + '\n' +
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'+12hrs in local time: ' + add12hours(inputDateString)
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);
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