JavaScript Calendar Premaker

Hi there all, I am a beginner to JavaScript and I need your help guys.

I have here a Calendar Premaker script that makes a basic calendar, what I want to add is a week number right on the left side, I found a ISO Standard (ISO week date - Wikipedia ) that show some rules how it's calculated.

Can anyone help me to implement it?

var sMS = "Ianuarie,Februarie,Martie,Aprilie,Mai,Iunie,Iulie,August,Septembrie,Octombrie,Noiembrie,Decembrie";
var sDS = "L,Ma,Mi,J,V,S,D";
var sHS = "1/1,8/3,1/5,25/12";
var pMS = "Scrie numele lunilor (separare prin virgula)\nSau lasa neschimbat!";
var pDS = "Scrie numele zilelor din saptamana (separare prin virgula)\nSau lasa neschimbat!";
var pHS = "Scrie sarbatorile, exemplu Z/L[,Z/L,Z/L...]";
var AppCap = "Calendar (pt. Adobe Illustrator CC)\n\n";
var iStr = "Pentru editare elemente:\n\n"+
   "Window -> Type -> Paragraph Styles\n"+
   "Window -> Type -> Character Styles\n"+
   "Window -> Swatches\n\n";
var pStr = AppCap+"Scrie anul.\nExemplu: 2019";
Year = 2019;
Year = prompt(pStr, Year); 
if(Year>2000 && Year<2100 && Year != null) {
MS = prompt(AppCap+pMS, sMS);
if(MS){
MC = MS.split(',',12);
for(i=0;i<12;i++) if(MC==null) MC.push(' ');
for(i=0;i<12;i++) if(MC=='') MC=' ';
DS = prompt(AppCap+pDS, sDS);
if(DS) {
DC = DS.split(',',7);
for(i=0;i<7;i++) if(DC==null) DC.push(' ');
for(i=0;i<7;i++) if(DC=='') DC=' ';
HS = prompt(AppCap+pHS, sHS);
if(HS == '') HS = ' ';
if(HS) {
HC = HS.split(',');
HD = Array();
for(i=0;i<HC.length;i++) {
  DM = HC.split('/');
  HD.push(DM[0],DM[1]);
}
makeCalendar();
}
}
}
}
function makeCalendar() {
CellHeight = 20;
CellWidth  = 30;
MN = Array(31,(Year%4==0)?29:28,31,30,31,30,31,31,30,31,30,31);
FirstDay = Math.floor((Year-2001)*5/4%7);
FD = FirstDay;
var DocTop = CellHeight*52;
var docRef = documents.add(DocumentColorSpace.CMYK,CellWidth*18,DocTop+CellHeight*3);
// 
waitRef = docRef.textFrames.add();
waitRef.contents = "Procesare...\n ©️ PRINTCO";
waitRef.top = DocTop;
waitRef.left = 10;
waitRef.height = 100;
waitRef.width = 300;
redraw();
//
docRef.swatches.removeAll();
try{docRef.characterStyles.removeAll()} catch(e){}
var nColor = new CMYKColor();
var nSpotColor = new SpotColor();
var DefaultSpot = docRef.spots.add();
nColor.cyan = 90;
nColor.magenta = 60;
nColor.yellow = 0;
nColor.black = 0;
DefaultSpot.name = "Zile";
DefaultSpot.colorType = ColorModel.PROCESS;
DefaultSpot.color = nColor;
var HolidaySpot = docRef.spots.add();
nColor.cyan = 0;
nColor.magenta = 90;
nColor.yellow = 60;
nColor.black = 0;
HolidaySpot.name = "Sarbatori";
HolidaySpot.colorType = ColorModel.PROCESS;
HolidaySpot.color = nColor;
var DaySpot = docRef.spots.add();
nColor.cyan = 0;
nColor.magenta = 0;
nColor.yellow = 0;
nColor.black = 70;
DaySpot.name = "Color of caption of week day";
DaySpot.colorType = ColorModel.PROCESS;
DaySpot.color = nColor;
var HolydayDaySpot = docRef.spots.add();
nColor.cyan = 0;
nColor.magenta = 60;
nColor.yellow = 20;
nColor.black = 50;
HolydayDaySpot.name = "Color of caption of weekend";
HolydayDaySpot.colorType = ColorModel.PROCESS;
HolydayDaySpot.color = nColor;
var CaptionSpot = docRef.spots.add();
nColor.cyan = 0;
nColor.magenta = 0;
nColor.yellow = 0;
nColor.black = 100;
CaptionSpot.name = "Color of caption of month";
CaptionSpot.colorType = ColorModel.PROCESS;
CaptionSpot.color = nColor;
var charAttr;
var paraAttr;
var DefaultStyle = docRef.characterStyles.add("Week day");
var HolidayStyle = docRef.characterStyles.add("Holyday");
var DayCapStyle = docRef.characterStyles.add("Caption of week day");
var HolydayCapStyle = docRef.characterStyles.add("Caption of weekend");
var CaptionsStyle = docRef.characterStyles.add("Caption of month");
charAttr = DefaultStyle.characterAttributes;
//charAttr.size = 14;
nSpotColor.spot = DefaultSpot;
charAttr.fillColor = nSpotColor;
charAttr = HolidayStyle.characterAttributes;
//charAttr.size = 14;
nSpotColor.spot = HolidaySpot;
charAttr.fillColor = nSpotColor;
charAttr = DayCapStyle.characterAttributes;
//charAttr.size = 14;
nSpotColor.spot = DaySpot;
charAttr.fillColor = nSpotColor;
charAttr = HolydayCapStyle.characterAttributes;
//charAttr.size = 14;
nSpotColor.spot = HolydayDaySpot;
charAttr.fillColor = nSpotColor;
charAttr = CaptionsStyle.characterAttributes;
//charAttr.size = 14;
nSpotColor.spot = CaptionSpot;
charAttr.fillColor = nSpotColor;
var paraDayStyle = docRef.paragraphStyles.add("Dates");
paraAttr = paraDayStyle.paragraphAttributes;
paraAttr.justification = Justification.RIGHT;
var paraWeekDayStyle = docRef.paragraphStyles.add("Days of week");
paraAttr = paraWeekDayStyle.paragraphAttributes;
paraAttr.justification = Justification.RIGHT;
var paraMonthStyle = docRef.paragraphStyles.add("Months");
paraAttr = paraMonthStyle.paragraphAttributes;
paraAttr.justification = Justification.LEFT;
LeftMargin = CellWidth;
for(m=0; m<6; m++){
textRef = docRef.textFrames.add();
textRef.contents = MC;
textRef.top = DocTop - m*9*CellHeight+CellHeight*2;
textRef.left = CellWidth + LeftMargin;     
CaptionsStyle.applyTo(textRef.textRange)
paraMonthStyle.applyTo(textRef.paragraphs[0], true);
for(i=0; i<7; i++){
textRef = docRef.textFrames.add();
textRef.contents = DC;
textRef.top = DocTop - m*9*CellHeight+CellHeight;
textRef.left = i*CellWidth + LeftMargin;
(i<5) ? DayCapStyle.applyTo(textRef.textRange) : HolydayCapStyle.applyTo(textRef.textRange);
paraWeekDayStyle.applyTo(textRef.paragraphs[0], true);
} 
for(d=0; d<MN; d++){
textRef = docRef.textFrames.add();
textRef.contents = d+1;
textRef.top = DocTop - ((Math.floor((FD+d)/7)*CellHeight) + m*9*CellHeight);
textRef.left = (FD+d)%7*CellWidth + LeftMargin;
paraDayStyle.applyTo(textRef.paragraphs[0], true);
if ((FD+d+1)%7) DefaultStyle.applyTo(textRef.textRange);
else            HolidayStyle.applyTo(textRef.textRange);
if (isHoliday(d+1,m+1)) HolidayStyle.applyTo(textRef.textRange);
}
FD = (FD+d)%7;
}
LeftMargin = CellWidth*9;
for(m=6; m<12; m++){
textRef = docRef.textFrames.add();
textRef.contents = MC;
textRef.top = DocTop - (m-6)*9*CellHeight+CellHeight*2;
textRef.left = CellWidth + LeftMargin;     
CaptionsStyle.applyTo(textRef.textRange)
paraMonthStyle.applyTo(textRef.paragraphs[0], true);
for(i=0; i<7; i++){
textRef = docRef.textFrames.add();
textRef.contents = DC;
textRef.top = DocTop - (m-6)*9*CellHeight+CellHeight;
textRef.left = i*CellWidth + LeftMargin;     
(i<5) ? DayCapStyle.applyTo(textRef.textRange) : HolydayCapStyle.applyTo(textRef.textRange);
paraWeekDayStyle.applyTo(textRef.paragraphs[0], true);
} 
for(d=0; d<MN; d++){
textRef = docRef.textFrames.add();
textRef.contents = d+1;
textRef.top = DocTop - ((Math.floor((FD+d)/7)*CellHeight) + (m-6)*9*CellHeight);
textRef.left = (FD+d)%7*CellWidth + LeftMargin;
paraDayStyle.applyTo(textRef.paragraphs[0], true);
if ((FD+d+1)%7) DefaultStyle.applyTo(textRef.textRange);
else            HolidayStyle.applyTo(textRef.textRange);
if (isHoliday(d+1,m+1)) HolidayStyle.applyTo(textRef.textRange);
}
FD = (FD+d)%7;
}
waitRef.remove();
redraw();
alert(iStr);
}
function isHoliday(day,month)
{
var i;
for(i=0; i<HD.length; i+=2){
if(day==HD && month==HD[i+1]) return true;
}
return false;
}