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Diffstat (limited to '')
-rw-r--r-- | static/lib.js | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/static/lib.js b/static/lib.js new file mode 100644 index 00000000..a6f1892b --- /dev/null +++ b/static/lib.js @@ -0,0 +1,132 @@ +'use strict'; +/* + General procedures which in theory could be used anywhere. + */ + +/* ----- Date Extensions ---------------------------- */ + +/* + Extensions to Javascript's Date to allow representing times + with different timezones. Currently only UTC and local time + are supported, but more should be able to be added. + + NOTE that only the raw `get' (and NOT the `getUTC') methods + should be used on these objects, and that the reported timezone + is quite often wrong. + */ + +function parseDate(str) { + let year, month, day, hour=false, minute, second=0, utc; + + let end = str.length - 1; + if (str[end] == 'Z') { + utc = true; + str = str.substring(0, end); + }; + + switch (str.length) { + case '2020-01-01T13:37:00'.length: + second = str.substr(17,2); + case '2020-01-01T13:37'.length: + hour = str.substr(11,2); + minute = str.substr(14,2); + case '2020-01-01'.length: + year = str.substr(0,4); + month = str.substr(5,2) - 1; + day = str.substr(8,2); + break; + default: + throw 'Bad argument'; + } + + let date; + if (hour) { + date = new Date(year, month, day, hour, minute, second); + date.utc = utc; + date.dateonly = false; + } else { + date = new Date(year, month, day); + date.dateonly = true; + } + return date; +} + +function copyDate(date) { + let d = new Date(date); + d.utc = date.utc; + d.dateonly = date.dateonly; + return d; +} + +function to_local(date) { + if (! date.utc) return date; + + return new Date(date.getTime() - date.getTimezoneOffset() * 60 * 1000); +} + +/* -------------------------------------------------- */ + +function makeElement (name, attr={}) { + let element = document.createElement(name); + for (let [key, value] of Object.entries(attr)) { + element[key] = value; + } + return element; +} + +function round_time (time, fraction) { + let scale = 1 / fraction; + return Math.round (time * scale) / scale; +} + +/* only used by the bar. + Events use the start and end time of their container, but since the bar + is moving between containers that is clumsy. + Just doing (new Date()/(86400*1000)) would be nice, but there's no good + way to get the time in the current day. + */ +function date_to_percent (date) { + return (date.getHours() + (date.getMinutes() / 60)) * 100/24; +} + +/* if only there was such a thing as a let to wrap around my lambda... */ +/* js infix to not collide with stuff generated backend */ +const gensym = (counter => (prefix="gensym") => prefix + "js" + ++counter)(0) + +function setVar(str, val) { + document.documentElement.style.setProperty("--" + str, val); +} + + + +function datepad(thing, width=2) { + return (thing + "").padStart(width, "0"); +} + +function format_date(date, str) { + let fmtmode = false; + let outstr = ""; + for (var i = 0; i < str.length; i++) { + if (fmtmode) { + switch (str[i]) { + /* Moves the date into local time. */ + case 'L': date = to_local(date); break; + case 'Y': outstr += datepad(date.getFullYear(), 4); break; + case 'm': outstr += datepad(date.getMonth() + 1); break; + case 'd': outstr += datepad(date.getDate()); break; + case 'H': outstr += datepad(date.getHours()); break; + case 'M': outstr += datepad(date.getMinutes()); break; + case 'S': outstr += datepad(date.getSeconds()); break; + case 'Z': if (date.utc) outstr += 'Z'; break; + } + fmtmode = false; + } else if (str[i] == '~') { + fmtmode = true; + } else { + outstr += str[i]; + } + } + return outstr; +} +Object.prototype.format = function () { return this; } /* any number of arguments */ +Date.prototype.format = function (str) { return format_date (this, str); } |