Get Day From Date with Javascript

dateToDay.js

// https://www.quora.com/How-do-I-calculate-the-day-from-dates
// implemented algo from Aayush-Chaudhry

const DAYS = ['Sunday','Monday','Tuesday','Wednesday','Thursday','Friday'];

function getDate(date)
{
  var brokenDate = date.split(" ");
  var givenDate = parseInt(brokenDate[0]);
  var givenMonth = brokenDate[1].toLowerCase();
  //console.log(givenMonth);
  var givenYear = parseInt(brokenDate[2]);
  //console.log(givenDate);
  var monthNumber = getMonthNumber(givenMonth,givenYear);
//console.log(monthNumber);
  var f = parseInt(givenYear/100);
  var l = parseInt(givenYear-(f*100));
  var l4 = parseInt((givenYear-(f*100))/4);

  var century = getCentury(f);

//  console.log(f+' '+l+' '+l4+' '+century);
  var res = (givenDate+monthNumber+century+l4+l)%7;

  console.log("Given Date is "+DAYS[res]);

}

function leapYearCheck(year)
{
  if( (year%100 !== 0  && year%4 === 0) || year%400 === 0) return true;
  else return false;
}

function getMonthNumber(givenMonth,givenYear)
{

  if(leapYearCheck(givenYear))
  {
    //6 2 3 6 1 4 6 2 5 0 3 5
    //console.log("It's a Leap Year "+givenMonth);
    if( 'january april july'.search(givenMonth) !== -1 ) return 6;
    if( 'february augest'.search(givenMonth) !== -1 ) return 2;
    if( 'march november'.search(givenMonth) !== -1 ) return 3;
    if( 'may'.search(givenMonth) !== -1 ) return 1;
    if( 'june'.search(givenMonth) !== -1 ) return 4;
    if( 'september december'.search(givenMonth) !== -1 ) return 5;
    if( 'october'.search(givenMonth) !== -1 ) return 0;

  }
  else {
    //0 3 3 6 1 4 6 2 5 0 3 5

    if( 'january october'.search(givenMonth) !== -1 ) return 0;
    if( 'february march november '.search(givenMonth) !== -1 ) return 3;
    if( 'april july'.search(givenMonth) !== -1 ) return 6;
    if( 'may'.search(givenMonth) !== -1 ) return 1;
    if( 'june'.search(givenMonth) !== -1 ) return 4;
    if( 'augest'.search(givenMonth) !== -1 ) return 2;
    if( 'september december'.search(givenMonth) !== -1 ) return 0;



  }

}

function getCentury(num){
  if(num%4 == 0) return 6;
  else if(num%4 == 1) return 4;
  else if(num%4 == 2) return 2;
  else if(num%4 == 3) return 0;
}