comparación de fechas con javascript

Question

tengo dos fechas en javascript:

var first = '2012-11-21'; 
var second = '2012-11-03'; 

me gustaría hacer:

if(first > second){ 
    //... 
} 

cómo es la mejor manera para esto, sin biblioteca externa?

Answer 1

if((new Date(first).getTime() > new Date(second).getTime())) 
{ 
    ---------------------------------- 
} 

Answer 2

Debido a su formato de fecha, puede utilizar este código:

if(parseInt(first.replace(/-/g,""),10) > parseInt(second.replace(/-/g,""),10)){ 
    //... 
} 

Se comprobará si 20121121 número es más grande que 20121103 o no.

Answer 3

Si las fechas son cadenas en una estricta formato yyyy-mm-dd como se muestra en la pregunta entonces su código funcionará tal cual, sin convertir a los objetos de fecha o números:

if(first > second){ 

... hará un lexographic (es decir, , "orden del diccionario" alfanumérico) comparación de cadenas - que comparará los primeros caracteres de cada cadena, luego los segundos caracteres de cada cadena, etc. Lo cual dará el resultado que desea ...

Answer 4

Utilice esta función para comparar fechas en javascript:

function fn_DateCompare(DateA, DateB) { 
     var a = new Date(DateA); 
     var b = new Date(DateB); 

     var msDateA = Date.UTC(a.getFullYear(), a.getMonth()+1, a.getDate()); 
     var msDateB = Date.UTC(b.getFullYear(), b.getMonth()+1, b.getDate()); 

     if (parseFloat(msDateA) < parseFloat(msDateB)) 
     return -1; // less than 
     else if (parseFloat(msDateA) == parseFloat(msDateB)) 
     return 0; // equal 
     else if (parseFloat(msDateA) > parseFloat(msDateB)) 
     return 1; // greater than 
     else 
     return null; // error 
    } 

Answer 5

Puede hacerlo de esta manera, no tendrán ningún problema:

var date1 = new Date('2013-07-30'); 
var date2 = new Date('2013-07-30'); 

if(date1 === date2){ console.log("both are equal");} //it does not work 
==>undefined //result 
if(+date1 === +date2){ console.log("both are equal");} //do it this way! 
//(use + prefix for a variable that holds a date value) 
==> both are equal //result 

Nota: - no se olvide de usar un prefijo +

Answer 6

La mejor manera es,

var first = '2012-11-21'; 
var second = '2012-11-03'; 

if (new Date(first) > new Date(second) { 
    ..... 
} 

Answer 7

puede hacerlo de esta manera también.

if (dateFormat(first, "yyyy-mm-dd") > dateFormat(second, "yyyy-mm-dd")) { 
     console.log("done"); 
} 

O

if (dateFormat(first, "mm-dd-yyyy") > dateFormat(second, "mm-dd-yyyy")) { 
     console.log("done"); 
} 

yo uso siguiente plug-in para dateFormat()

 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); 
    };