81 lines
2.1 KiB
JavaScript
81 lines
2.1 KiB
JavaScript
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/**
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* Module exports.
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*/
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module.exports = weekdayRange;
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/**
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* Only the first parameter is mandatory. Either the second, the third, or both
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* may be left out.
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*
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* If only one parameter is present, the function yeilds a true value on the
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* weekday that the parameter represents. If the string "GMT" is specified as
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* a second parameter, times are taken to be in GMT, otherwise in local timezone.
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*
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* If both wd1 and wd1 are defined, the condition is true if the current weekday
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* is in between those two weekdays. Bounds are inclusive. If the "GMT" parameter
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* is specified, times are taken to be in GMT, otherwise the local timezone is
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* used.
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*
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* Valid "weekday strings" are:
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*
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* SUN MON TUE WED THU FRI SAT
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*
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* Examples:
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*
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* ``` js
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* weekdayRange("MON", "FRI")
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* true Monday trhough Friday (local timezone).
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*
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* weekdayRange("MON", "FRI", "GMT")
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* same as above, but GMT timezone.
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*
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* weekdayRange("SAT")
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* true on Saturdays local time.
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*
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* weekdayRange("SAT", "GMT")
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* true on Saturdays GMT time.
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*
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* weekdayRange("FRI", "MON")
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* true Friday through Monday (note, order does matter!).
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* ```
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*
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*
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* @param {String} wd1 one of the weekday strings.
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* @param {String} wd2 one of the weekday strings.
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* @param {String} gmt is either the string: GMT or is left out.
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* @return {Boolean}
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*/
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const dayOrder = { "SUN": 0, "MON": 1, "TUE": 2, "WED": 3, "THU": 4, "FRI": 5, "SAT": 6 };
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function weekdayRange (wd1, wd2, gmt) {
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var useGMTzone = (wd2 == "GMT" || gmt == "GMT"),
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todaysDay = getTodaysDay(useGMTzone),
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wd1Index = dayOrder[wd1] || -1,
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wd2Index = dayOrder[wd2] || -1,
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result = false;
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if (wd2Index < 0) {
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result = (todaysDay == wd1Index);
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} else {
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if (wd1Index <= wd2Index) {
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result = valueInRange(wd1Index, todaysDay, wd2Index);
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} else {
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result = valueInRange(wd1Index, todaysDay, 6) || valueInRange(0, todaysDay, wd2Index);
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}
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}
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return result;
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}
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function getTodaysDay (gmt) {
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return (gmt ? (new Date()).getUTCDay() : (new Date()).getDay());
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}
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// start <= value <= finish
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function valueInRange (start, value, finish) {
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return (start <= value) && (value <= finish);
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}
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