How to make a delivery date estimator that avoids weekends for a Shopify product page

javascript for delivery date

$(document).ready(function() {

  function calculateHMSleft() {
    var d = new Date();
    var weekday = new Array(7);
    weekday[0] = "Sunday";
    weekday[1] = "Monday";
    weekday[2] = "Tuesday";
    weekday[3] = "Wednesday";
    weekday[4] = "Thursday";
    weekday[5] = "Friday";
    weekday[6] = "Saturday";
    var monthday = new Array(12);
    monthday[0] = "January";
    monthday[1] = "February";
    monthday[2] = "March";
    monthday[3] = "April";
    monthday[4] = "May";
    monthday[5] = "June";
    monthday[6] = "July";
    monthday[7] = "August";
    monthday[8] = "September";
    monthday[9] = "October";
    monthday[10] = "November";
    monthday[11] = "December";
    //calculate

    var now = new Date();
    var hoursleft = 12-now.getHours();
    console.log(hoursleft);
    var minutesleft = 59-now.getMinutes();
    var secondsleft = 59-now.getSeconds();

    //format 0 prefixes
    if(minutesleft<10) minutesleft = "0"+minutesleft;
    if(secondsleft<10) secondsleft = "0"+secondsleft;

    if (hoursleft < 0) {
      var hoursleft = hoursleft + 24
    }

    //display
    $('#HMSremaining').html(hoursleft+" hours and "+minutesleft+" minutes");

    if (hoursleft > 12) {
      if (d.getDay() == 0 || d.getDay() <= 2) {
          d.setHours(d.getHours() + 72);
          var deliver = weekday[d.getDay()];
          var day = d.getDate();
          var month = monthday[d.getMonth()];
          document.getElementById("deliveryday").innerHTML = deliver + ' ' + month + ' ' + day;
      } else if (d.getDay() == 3) {
          d.setHours(d.getHours() + 120);
          var deliver = weekday[d.getDay()];
          var day = d.getDate();
          var month = monthday[d.getMonth()];
          document.getElementById("deliveryday").innerHTML = deliver + ' ' + month + ' ' + day;
      } else {
          d.setHours(d.getHours() + 96);
          var deliver = weekday[d.getDay()];
          var day = d.getDate();
          var month = monthday[d.getMonth()];
          document.getElementById("deliveryday").innerHTML = deliver + ' ' + month + '-' + day;
      }
    } else {
      if (d.getDay() > 0 || d.getDay() <= 3) {
          d.setHours(d.getHours() + 48);
          var deliver = weekday[d.getDay()];
          var day = d.getDate();
          var month = monthday[d.getMonth()];
          document.getElementById("deliveryday").innerHTML = deliver + ' ' + month + ' ' + day;
      } else if (d.getDay() == 0) {
          d.setHours(d.getHours() + 48);
          var deliver = weekday[d.getDay()];
          var day = d.getDate();
          var month = monthday[d.getMonth()];
          document.getElementById("deliveryday").innerHTML = deliver + ' ' + month + ' ' + day;
      } else {
          d.setHours(d.getHours() + 96);
          var deliver = weekday[d.getDay()];
          var day = d.getDate();
          var month = monthday[d.getMonth()];
          document.getElementById("deliveryday").innerHTML = deliver + ' ' + month + '-' + day;
      }
    }
  }

  calculateHMSleft();
  setInterval(calculateHMSleft, 60000);

});