So not so long ago I made my own booking system which displays a calendar on a page with the dates that have been booked but I noticed recently, if one of the bookings goes across two months e.g. 29th March to 4th April the whole thing just crashes / doesn't load and I'm really confused as to why. The date still gets entered into my database but then it breaks.
Here is the code for displaying the calendar (Note: I got most of this code from a CodePen and edited it accordingly):
<?php
session_start();
ob_start();
$host = "myhostname"; // Host name
$username = "myusername"; // Mysql username
$password = ""; // Mysql password
$db_name = "mydatabase"; // Database name
$tbl_name = "booking"; // Table name
// Connect to server and select databse.
$conn = mysqli_connect($host, $username, $password)or die("cannot connect");
mysqli_select_db($conn, $db_name)or die("cannot select DB");
$sql = "SELECT * FROM $tbl_name";
$result = mysqli_query($conn, $sql);
?>
<script>
!function() {
var today = moment();
function Calendar(selector, events) {
this.el = document.querySelector(selector);
this.events = events;
this.current = moment().date(1);
this.events.forEach(function(ev) {
ev.date = moment(ev.date);
});
this.draw();
var current = document.querySelector('.today');
if(current) {
var self = this;
window.setTimeout(function() {
self.openDay(current);
}, 500);
}
}
Calendar.prototype.draw = function() {
//Create Header
this.drawHeader();
//Draw Month
this.drawMonth();
}
Calendar.prototype.drawHeader = function() {
var self = this;
if(!this.header) {
//Create the header elements
this.header = createElement('div', 'header');
this.header.className = 'header';
this.title = createElement('h3');
var right = createElement('div', 'right');
right.addEventListener('click', function() { self.nextMonth(); });
var left = createElement('div', 'left');
left.addEventListener('click', function() { self.prevMonth(); });
document.addEventListener("keydown", function(event) {
if (event.keyCode === 39) {
event.preventDefault();
self.nextMonth();
} else if (event.keyCode === 37) {
event.preventDefault();
self.prevMonth();
}
});
//Append the Elements
this.header.appendChild(this.title);
this.header.appendChild(right);
this.header.appendChild(left);
this.el.appendChild(this.header);
}
this.title.innerHTML = this.current.format('MMMM YYYY');
}
Calendar.prototype.drawMonth = function() {
var self = this;
if(this.month) {
this.oldMonth = this.month;
this.oldMonth.className = 'month out ' + (self.next ? 'next' : 'prev');
this.oldMonth.addEventListener('webkitAnimationEnd', function() {
self.oldMonth.parentNode.removeChild(self.oldMonth);
self.month = createElement('div', 'month');
self.backFill();
self.currentMonth();
self.fowardFill();
self.el.appendChild(self.month);
window.setTimeout(function() {
self.month.className = 'month in ' + (self.next ? 'next' : 'prev');
}, 16);
});
} else {
this.month = createElement('div', 'month');
this.el.appendChild(this.month);
this.backFill();
this.currentMonth();
this.fowardFill();
this.month.className = 'month new';
}
}
Calendar.prototype.backFill = function() {
var clone = this.current.clone();
var dayOfWeek = clone.day();
if(!dayOfWeek) { return; }
clone.subtract('days', dayOfWeek);
for(var i = dayOfWeek; i > 1 ; i--) {
this.drawDay(clone.add('days', 1));
}
}
Calendar.prototype.fowardFill = function() {
var clone = this.current.clone().add('months', 1).subtract('days', 1);
var dayOfWeek = clone.day();
if(dayOfWeek === 7) { return; }
for(var i = dayOfWeek; i < 7 ; i++) {
this.drawDay(clone.add('days', 1));
}
}
Calendar.prototype.currentMonth = function() {
var clone = this.current.clone();
while(clone.month() === this.current.month()) {
this.drawDay(clone);
clone.add('days', 1);
}
}
Calendar.prototype.getWeek = function(day) {
if(!this.week || day.day() === 1) {
this.week = createElement('div', 'week');
this.month.appendChild(this.week);
}
}
Calendar.prototype.drawDay = function(day) {
var self = this;
this.getWeek(day);
//Outer Day
var outer = createElement('div', this.getDayClass(day));
outer.addEventListener('click', function() {
self.openDay(this);
});
//Day Name
var name = createElement('div', 'day-name', day.format('ddd'));
//Day Number
var number = createElement('div', 'day-number', day.format('DD'));
//Events
var events = createElement('div', 'day-events');
this.drawEvents(day, events);
outer.appendChild(name);
outer.appendChild(number);
outer.appendChild(events);
this.week.appendChild(outer);
}
Calendar.prototype.drawEvents = function(day, element) {
if(day.month() === this.current.month()) {
var todaysEvents = this.events.reduce(function(memo, ev) {
if(ev.date.isSame(day, 'day')) {
memo.push(ev);
}
return memo;
}, []);
todaysEvents.forEach(function(ev) {
var evSpan = createElement('span', ev.color);
element.appendChild(evSpan);
});
}
}
Calendar.prototype.getDayClass = function(day) {
classes = ['day'];
if(day.month() !== this.current.month()) {
classes.push('other');
} else if (today.isSame(day, 'day')) {
classes.push('today');
}
return classes.join(' ');
}
Calendar.prototype.openDay = function(el) {
var details, arrow;
var dayNumber = +el.querySelectorAll('.day-number')[0].innerText || +el.querySelectorAll('.day-number')[0].textContent;
var day = this.current.clone().date(dayNumber);
var currentOpened = document.querySelector('.details');
//Check to see if there is an open detais box on the current row
if(currentOpened && currentOpened.parentNode === el.parentNode) {
details = currentOpened;
arrow = document.querySelector('.arrow');
} else {
//Close the open events on differnt week row
//currentOpened && currentOpened.parentNode.removeChild(currentOpened);
if(currentOpened) {
currentOpened.addEventListener('webkitAnimationEnd', function() {
currentOpened.parentNode.removeChild(currentOpened);
});
currentOpened.addEventListener('oanimationend', function() {
currentOpened.parentNode.removeChild(currentOpened);
});
currentOpened.addEventListener('msAnimationEnd', function() {
currentOpened.parentNode.removeChild(currentOpened);
});
currentOpened.addEventListener('animationend', function() {
currentOpened.parentNode.removeChild(currentOpened);
});
currentOpened.className = 'details out';
}
//Create the Details Container
details = createElement('div', 'details in');
//Create the arrow
var arrow = createElement('div', 'arrow');
//Create the event wrapper
details.appendChild(arrow);
el.parentNode.appendChild(details);
}
var todaysEvents = this.events.reduce(function(memo, ev) {
if(ev.date.isSame(day, 'day')) {
memo.push(ev);
}
return memo;
}, []);
this.renderEvents(todaysEvents, details);
arrow.style.left = el.offsetLeft - el.parentNode.offsetLeft + 27 + 'px';
}
Calendar.prototype.renderEvents = function(events, ele) {
//Remove any events in the current details element
var currentWrapper = ele.querySelector('.events');
var wrapper = createElement('div', 'events in' + (currentWrapper ? ' new' : ''));
events.forEach(function(ev) {
var div = createElement('div', 'event');
var span = createElement('span', '', ev.eventName);
div.appendChild(span);
wrapper.appendChild(div);
});
if(!events.length) {
var div = createElement('div', 'event empty');
var span = createElement('span', '', 'No Booking');
div.appendChild(span);
wrapper.appendChild(div);
}
if(currentWrapper) {
currentWrapper.className = 'events out';
currentWrapper.addEventListener('webkitAnimationEnd', function() {
currentWrapper.parentNode.removeChild(currentWrapper);
ele.appendChild(wrapper);
});
currentWrapper.addEventListener('oanimationend', function() {
currentWrapper.parentNode.removeChild(currentWrapper);
ele.appendChild(wrapper);
});
currentWrapper.addEventListener('msAnimationEnd', function() {
currentWrapper.parentNode.removeChild(currentWrapper);
ele.appendChild(wrapper);
});
currentWrapper.addEventListener('animationend', function() {
currentWrapper.parentNode.removeChild(currentWrapper);
ele.appendChild(wrapper);
});
} else {
ele.appendChild(wrapper);
}
}
Calendar.prototype.drawLegend = function() {
var calendars = this.events.map(function(e) {
return e.calendar + '|' + e.color;
}).reduce(function(memo, e) {
if(memo.indexOf(e) === -1) {
memo.push(e);
}
return memo;
}, []).forEach(function(e) {
var parts = e.split('|');
var entry = createElement('span', 'entry ' + parts[1], parts[0]);
});
}
Calendar.prototype.nextMonth = function() {
this.current.add('months', 1);
this.next = true;
this.draw();
}
Calendar.prototype.prevMonth = function() {
this.current.subtract('months', 1);
this.next = false;
this.draw();
}
window.Calendar = Calendar;
function createElement(tagName, className, innerText) {
var ele = document.createElement(tagName);
if(className) {
ele.className = className;
}
if(innerText) {
ele.innderText = ele.textContent = innerText;
}
return ele;
}
}();
!function() {
var data = [
<?php
$colour = 'blue';
while($rows = mysqli_fetch_array($result)) {
if($rows['status'] == 'Confirmed') {
$colour = 'red';
} else {
$colour = 'blue';
}
?>
{ eventName: 'Booking Start', calendar: 'Booking <?php echo $rows['status']; ?>', color: '<?php echo $colour; ?>', date: '<?php echo $rows['arrive_date']?>'},
<?php
$date = date('Y-m-d', strtotime($rows['arrive_date']));
while ($date < date('Y-m-d', strtotime($rows['depart_date']. '-1 day'))) {
$date++;
?>
{ eventName: 'Booked', calendar: 'Booking <?php echo $rows['status']; ?>', color: '<?php echo $colour; ?>', date: '<?php echo $date;?>'},
<?php
}
?>
{ eventName: 'Booking End', calendar: 'Booking <?php echo $rows['status']; ?>', color: '<?php echo $colour; ?>', date: '<?php echo $rows['depart_date']; ?>'},
<?php
}
?>
];
var calendar = new Calendar('#calendar', data);
}();
</script>
EDIT: In case you need further help this is what an example looks like from the table in the database: 
I can't work out what is causing this problem, I believe it is something to do with the events but I don't know. I was hoping someone a little more experienced could help me out a little.
To see what it looks like visually you can see it live here: https://ryan-simms.com/booking/bookings
EDIT: I just found out, doing a test, that if I put in 28th February to the 1st March it doesn't crash but if I change it so it ends on the 2nd March it crashes, really odd.
