85 lines
2.5 KiB
JavaScript
85 lines
2.5 KiB
JavaScript
function parseNumber(s) {
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return parseInt(s, 10);
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}
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//in seconds
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var hours = 3600;
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var minutes = 60;
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//take date (year, month, day) and time (hour, minutes, seconds) digits in UTC
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//and return a timestamp in seconds
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function parseDateTimeParts(dateParts, timeParts) {
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dateParts = dateParts.map(parseNumber);
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timeParts = timeParts.map(parseNumber);
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var year = dateParts[0];
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var month = dateParts[1] - 1;
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var day = dateParts[2];
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var hours = timeParts[0];
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var minutes = timeParts[1];
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var seconds = timeParts[2];
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var date = Date.UTC(year, month, day, hours, minutes, seconds, 0);
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var timestamp = date / 1000;
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return timestamp;
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}
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//parse date with "2004-09-04T23:39:06-08:00" format,
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//one of the formats supported by ISO 8601, and
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//convert to utc timestamp in seconds
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function parseDateWithTimezoneFormat(dateTimeStr) {
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var dateParts = dateTimeStr.substr(0, 10).split('-');
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var timeParts = dateTimeStr.substr(11, 8).split(':');
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var timezoneStr = dateTimeStr.substr(19, 6);
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var timezoneParts = timezoneStr.split(':').map(parseNumber);
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var timezoneOffset = (timezoneParts[0] * hours) +
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(timezoneParts[1] * minutes);
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var timestamp = parseDateTimeParts(dateParts, timeParts);
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//minus because the timezoneOffset describes
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//how much the described time is ahead of UTC
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timestamp -= timezoneOffset;
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if(typeof timestamp === 'number' && !isNaN(timestamp)) {
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return timestamp;
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}
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}
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//parse date with "YYYY:MM:DD hh:mm:ss" format, convert to utc timestamp in seconds
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function parseDateWithSpecFormat(dateTimeStr) {
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var parts = dateTimeStr.split(' '),
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dateParts = parts[0].split(':'),
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timeParts = parts[1].split(':');
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var timestamp = parseDateTimeParts(dateParts, timeParts);
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if(typeof timestamp === 'number' && !isNaN(timestamp)) {
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return timestamp;
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}
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}
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function parseExifDate(dateTimeStr) {
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//some easy checks to determine two common date formats
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//is the date in the standard "YYYY:MM:DD hh:mm:ss" format?
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var isSpecFormat = dateTimeStr.length === 19 &&
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dateTimeStr.charAt(4) === ':';
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//is the date in the non-standard format,
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//"2004-09-04T23:39:06-08:00" to include a timezone?
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var isTimezoneFormat = dateTimeStr.length === 25 &&
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dateTimeStr.charAt(10) === 'T';
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var timestamp;
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if(isTimezoneFormat) {
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return parseDateWithTimezoneFormat(dateTimeStr);
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}
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else if(isSpecFormat) {
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return parseDateWithSpecFormat(dateTimeStr);
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}
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}
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module.exports = {
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parseDateWithSpecFormat: parseDateWithSpecFormat,
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parseDateWithTimezoneFormat: parseDateWithTimezoneFormat,
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parseExifDate: parseExifDate
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};
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