Addition and subtraction of dates in JS

JavaScript implementation date subtraction Calculation function code instance, because there is no similar adddays method in C # in JS, so if you want to implement date addition and subtraction, you need to write the function to achieve.

Today even if the date in the JS add and subtract to make a summary, a total of two steps

The first step, the introduction of date.format.js, the role of this JS is to convert the date to the specified format, the code is as follows

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var dateformat = function () {var token =/d{1,4}|m{1,4}|yy (?: yy)? | ([HHMSTT]) 1?| [llosz]|] [^"]*"|' [^ ']* '/g, timezone =/b (?: [Pmcea][sdp]t| (?:P acific| mountain| central| eastern| Atlantic) (?: standard| Daylight| prevailing) time| (?: gmt| UTC) (?: [-+]d{4})? b/g, timezoneclip =/[^-+da-z]/g, pad = function (val, len) {val = String (val); len = Len | | 2; while (Val.length < le N) val = "0" + val; return Val; };  //regexes and supporting functions are cached through return function (date, closure, UTC) {var DF = mask Mat  //Can ' t provide UTC if you skip other args (Use the "UTC: Mask prefix) if (arguments.length = 1 && O Bject.prototype.toString.call (date) = = "[Object String]" &&!/d/.test (date) {mask = date; date = undefined;} &n Bsp Passing date through date applies date.parse, if necessary date = date? New Date: new Date; if (isNaN (date)) throw SyntaxError ("Invalid Date");   Mask = String (Df.masks[mask] | | | mask | | df.masks["Default"]);  //Allow setting the UTC argument via the Mask if (Mask.slice (0, 4) = = "UTC:") {mask = Mask.slice (4); UTC = True; }   var _ = UTC? "GETUTC": "get", D = date[_ + "date"] (), d = date[_ + "Day" (), M = date[_ + "Month"] (), y = date[_ + "Fullyear"] (), H = Date[_ + "Hours"] (), M = date[_ + "Minutes"] (), s = date[_ + "Seconds"] (), L = Date[_ + "milliseconds"] (), o = UTC? 0:date.gettimezoneoffset (), flags = {D:D, dd:pad (d), ddd:df.i18n.daynames[d], Dddd:df.i18n.daynames[d + 7], m:m + 1, Mm:pad (M + 1), mmm:df.i18n.monthnames[m], mmmm:df.i18n.monthnames[m +), yy:string (y). Slice (2), yyyy:y, h:h% 1 2 | | Hh:pad (h%), H:h, Hh:pad (h), M:m, Mm:pad (M), S:s, Ss:pad (s), L:pad (L, 3), L:pad (L > 99? Math.Round (L/10): L), T:h < 12? "A": "P", tt:h < 12? "AM": "PM", t:h < 12? "A": "P", Tt:h < 12? "AM": "PM", Z:UTC? "UTC": (String (date). Match (timezone) | | [""]). POPs (). replace (Timezoneclip, ""), O: (o > 0?) -" : "+") + pad (math.abs (o)/(Math.floor) + math.abs (o)%, 4), S: ["th", "st", "nd", "rd"][d% > 3? 0: (d% 10 0-d%!=) * d% 10]};   Return Mask.replace (token, function ($) {return $ in flags flags[$0]: $0.slice (1, $0.length-1);}); }; }();  //Some common Format Strings dateformat.masks = {"Default": "DDD mmm dd yyyy HH:MM:ss", ShortDate: "M/d/yy", Medi Umdate: "Mmm D, yyyy", longdate: "Mmmm d, yyyy", fulldate: "dddd, mmmm d, yyyy", Shorttime: "h:mm TT", Mediumtime: "H:mm:s S TT ", longtime:" H:mm:ss tt Z ", Isodate:" Yyyy-mm-dd ", Isotime:" HH:MM:ss ", Isodatetime:" Yyyy-mm-dd ' T ' HH:MM:ss ", ISOUTCD Atetime: "Utc:yyyy-mm-dd ' T ' HH:MM:ss ' Z '"};  //Internationalization strings dateformat.i18n = {daynames: ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "S Unday "," Monday "," Tuesday "," Wednesday "," Thursday "," Friday "," Saturday "], monthnames: [" A Few "," Feb "," Mar "," APR "," "M Ay "," June "," Aug "," Nov "," Sep "," Oct "," January "," Dec "," February "," March "," April "," may "," June "," July "," August "," September "," October "," November "," December "]};  /For convenience ... Date.prototype.format = function (mask, UTC) {return DateFormat (this, mask, UTC);

In the second step, the time is converted to milliseconds to add and subtract calculations, and then use the above JS to the specified date

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var nowdate = new Date (); Addition operation var ysdate = new Date (Nowdate.gettime () -30*24*60*60*1000). Format (' Yyyy-mm-dd '); Subtraction operation var yedate = new Date (Nowdate.gettime () -24*60*60*1000). Format (' yyyy-m-d ');

Through the above two steps to achieve, JS in the date of addition and subtraction, how simple it! Go ahead and try!

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