Custom slider by day

Please be a little more specific about your requirements.
For example, would it be enough if you had a color section that changes the wallpaper day by day?

if so : make a color-section and define one background-image as you like to have it ( cover image , bottom center etc. pp)
Give a unique ID to the color-section f.e.: customID
you have to know now the page id ( so that we don’t have to load the script on pages that don’t need it at all. ) (in my case it is page id 34024)
– the relative path to your images (imglocation)
Put this into your child-theme functions.php

add_action( 'wp_footer', 'schedule_bg_image' );
function schedule_bg_image() {
if(is_page(34024)){ 
?>
<script type="text/javascript">
var imglocation = "/wp-content/uploads/layerslider/Origami/";
 function ImageArray (n) {
   this.length = n;
   for (var i =1; i <= n; i++) {
     this[i] = ' '
   }
 }
image = new ImageArray(7);
image[0] = 'slide1.jpg'; // Sunday
image[1] = 'slide1.jpg'; // Monday
image[2] = 'slide2.jpg'; // Tuesday
image[3] = 'slide3.jpg'; // Wednesday
image[4] = 'slide4.jpg'; // Thursday
image[5] = 'slide1.jpg'; // Friday
image[6] = 'slide1.jpg'; // Saturday
var currentdate = new Date();
var imagenumber = currentdate.getDay();
document.getElementById('customID').style.backgroundImage = 'url(' + imglocation + image[imagenumber] + ')';
</script>
<?php
}
}

see here : https://webers-testseite.de/bg-scheduling/

first of all : have you adjusted the code to your settings:
The main thing for that error seams to be that you have forgotten the customID to set – because if that DOM Element does not exist – it is impossible to style it !!!
document.getElementById('customID') etc …
f.e. :

• have you done this (see comment above) : Give a unique ID to the color-section f.e.: customID – or what ever you like – but then it has to be synchronized with the script line mentioned above
• the code above is ment for child-theme functions.php – is that the place where you put in that code
• adjust the url line to define the place where the images are in: var imglocation = "/wp-content/uploads/layerslider/Origami/";
• the code above is for my installation. I don’t want to load it everywhere so i surrounded it by an if-clause concerning to my page-id.
  have you changed it to your page: if(is_page(34024)){