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From: "Mel Smith" <med_cutout_syntel@aol.com>
Newsgroups: comp.lang.javascript
Subject: Re: Date Conversion ?
Date: Fri, 20 Dec 2013 09:52:57 -0700
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Dr. J said:

> Show us your code, and we can think about whether they are reliably
> solved.

Hi Dr Stockton:

    Here's my latest iteration of my date checking function (which includes 
JJ's parsedate() function and Thomas' Math function usage to find lows and 
highs.

-Mel Smith

*********************************

function chkdate(stnd,cdate) {
// where stnd is either "ST" or "ND" and
// where cdate is in the form: mm-dd-yyyy or mm/dd/yyyy (read/write)
// global scrcols is currently 13
// global playdatecol is currently the third column (i.e., 2)

var lok = true ;
var i,j,scrtable,rows,cells,cell,numrows;
var playdatestr,playdateval ;
var datearray = [] ;
var low,high,nlen ;
var yr,mth,day ;  // generalized checking for a modified date
var lowdate,nlowyr,clowyr,nlowmth,clowmth,nlowday,clowday ;
var highdate,nhighyr,chighyr,nhighmth,chighmth,nhighday,chighday ;

if (partof("mm",cdate) && partof("dd",cdate) ) { // then no date was 
entered -- so start searching
   scrtable = getobj("iscrtable") ;
   rows = scrtable.rows ;
   numrows = rows.length ;

   for (i=4;i<numrows;i++) {
      cells = rows[i].cells ;
      if (cells.length < scrcols) continue ;  // some rows are separators 
and are one column wide
      cell = cells[playdatecol] ;
      playdatestr = cell.innerHTML ;
      // now convert this string to a numeric javascript date value
      playdateval = parseDate(playdatestr) ; // from JJ of my JS/ES group
      if (isNaN(playdateval)) {
         alert("Faulty PlayDate Value ?? at row: "+ i) ;
         continue ;
         }
      datearray.push(playdateval) ;
      }
   low  = Math.min.apply(Math,datearray) ;  // from Thomas Lahn of JS/ES 
group
   high = Math.max.apply(Math,datearray) ;  // ditto

   // now re-make this into a date vrbl -- rather than just a vrbl
   lowdate = new Date(low) ;
   highdate = new Date(high) ;

   // Now convert back into yr,mth, and cday

   nlowyr = lowdate.getFullYear() ;
   clowyr = nlowyr.toString() ;
   nlowmth = lowdate.getMonth() + 1 ;
   clowmth = strzero(nlowmth,2) ;   // width of 2
   nlowday = lowdate.getDate() ;
   clowday = strzero(nlowday,2) ;

   nhighyr = highdate.getFullYear() ;
   chighyr = nhighyr.toString() ;
   nhighmth = highdate.getMonth() + 1 ;
   chighmth = strzero(nhighmth,2) ;
   nhighday = highdate.getDate() ;
   chighday = strzero(nhighday,2) ;

   // Now replace dates in box with actual date in table
   if (stnd === "ST") {
      startdateinp.value = clowmth+"-"+clowday+"-"+clowyr ;
      }
   if (stnd === "ND") {
      enddateinp.value = chighmth+"-"+chighday+"-"+chighyr ;
      }
   return lok ;
   }

// Else we have a modified date field to examine

mth = +cdate.substr(0,2) ;
if (mth < 1 || mth > 12) return !lok ;

day = +cdate.substr(3,2) ;
if (day < 1 || day > 31) return !lok ;
// the above is not a complete check -- do better later

yr = +cdate.substr(6,4) ;
// today is a global date object of current day
if (yr < 2000 || yr > today.getFullYear()) return !lok ;

// now check presence of separators and allow '/' or '-'
if (!partof(cdate.substr(2,1),"/-")) return !lok ;
if (!partof(cdate.substr(5,1),"/-")) return !lok ;

return lok ;
}

function parseDate(dateStr) {
// by JJ of JS/ES group
// for "Mmm dd/yy" format, year 20nn only.
// converts to "Mmm dd yyyy" (good for FF, IE8, Chrome, Opera).
// returns NaN if dateStr is in invalid format.

var date = dateStr.replace(/([a-z]+ \d+)\/(\d+)/,"$1 20$2");
return (new Date(date)).valueOf();
}