js中日期的加減法

 　　JavaScript實現日期加減計算功能代碼實例，因為在js中沒有類似C#中的AddDays方法，所以要想實現日期加減的話，就需要自己寫函數來實現。

　　今天就算對JS中日期的加減法做個總結，一共兩步

　　第一步，引入date.format.js，這個JS的作用是將日期轉為指定的格式，代碼如下

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 var dateFormat = function () { var token = /d{1,4}|m{1,4}|yy(?:yy)?|([HhMsTt])1?|[LloSZ]|"[^"]*"|'[^']*'/g, timezone = /b(?:[PMCEA][SDP]T|(?:Pacific|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 < len) val = "0" + val; return val; };   // Regexes and supporting functions are cached through closure return function (date, mask, utc) { var dF = dateFormat;   // You can't provide utc if you skip other args (use the "UTC:" mask prefix) if (arguments.length == 1 && Object.prototype.toString.call(date) == "[object String]" && !/d/.test(date)) { mask = date; date = undefined; }   // Passing date through Date applies Date.parse, if necessary date = date ? new Date(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 + 12], yy: String(y).slice(2), yyyy: y, h: H % 12 || 12, hh: pad(H % 12 || 12), 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) || [""]).pop().replace(timezoneClip, ""), o: (o > 0 ? "-" : "+") + pad(Math.floor(Math.abs(o) / 60) * 100 + Math.abs(o) % 60, 4), S: ["th", "st", "nd", "rd"][d % 10 > 3 ? 0 : (d % 100 - d % 10 != 10) * d % 10] };   return mask.replace(token, function ($0) { return $0 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", mediumDate: "mmm d, yyyy", longDate: "mmmm d, yyyy", fullDate: "dddd, mmmm d, yyyy", shortTime: "h:MM TT", mediumTime: "h:MM:ss TT", longTime: "h:MM:ss TT Z", isoDate: "yyyy-mm-dd", isoTime: "HH:MM:ss", isoDateTime: "yyyy-mm-dd'T'HH:MM:ss", isoUtcDateTime: "UTC:yyyy-mm-dd'T'HH:MM:ss'Z'" };   // Internationalization strings dateFormat.i18n = { dayNames: [ "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" ], monthNames: [ "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec", "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" ] };   // For convenience... Date.prototype.format = function (mask, utc) { return dateFormat(this, mask, utc); };

　　第二步，將時間轉換為毫秒進行加減計算，然後再用上面的js的轉為指定的日期

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