Redirect to another URL based on the current date

redirect_date.js

/* configuration */
var redirectDays = [
  ['7/27/2018', 'https://dotcomboom.neocities.org'], 
  ['7/28', 'https://coolandgood.neocities.org']
]; /* mm/dd/yyyy or mm/dd format */
var milliseconds = 2000;

/* sleep function from https://www.sitepoint.com/delay-sleep-pause-wait/ */
function sleep(milliseconds) {
  var start = new Date().getTime();
  for (var i = 0; i < 1e7; i++) {
    if ((new Date().getTime() - start) > milliseconds){
      break;
    }
  }
}

/* count occurrences of character from https://stackoverflow.com/a/881147 */
String.prototype.count=function(s1) { 
    return (this.length - this.replace(new RegExp(s1,"g"), '').length) / s1.length;
}

/* now, determine today's date */
var today = new Date();
var dd = today.getDate();
var mm = today.getMonth()+1;
var yyyy = today.getFullYear();
var todaystr = mm + '/' + dd + '/' + yyyy;

console.log('Today is ' + todaystr);

/* add year to dates without it */
for (var i in redirectDays) {
  if (redirectDays[i][0].count('/') < 2) {
    redirectDays[i][0] = redirectDays[i][0] + '/' + yyyy
  } 
}

/* now we're ready to see if today has a redirect */
for (var i in redirectDays) {
  console.log(redirectDays[i][0] + ', ' + redirectDays[i][1]);
  if (redirectDays[i][0] == todaystr) {
    console.log('Found a match, now redirecting')
    sleep(milliseconds);
    window.location.href = redirectDays[i][1];
    break;
  } 
}