https://www.schullandheime.de/s/tc-www/js/captcha.js

1function getCimg(u, pr) {
2    var kU = 'https://city-map.com/cimg/s/';
3    var kP = '';
4    
5    var xhr = new XMLHttpRequest();
6	xhr.open("POST", kU, true);
7	xhr.setRequestHeader('Content-Type', 'multipart/form-data');
8	xhr.onreadystatechange = function() {
9   		if (this.readyState == 4 && this.status == 200) {
10   			// Response
11	      	var r = this.responseText;
12	      	var d = eval(r);
13	      	
14	      	if(typeof(d.captcha_image_url) != 'undefined') {
15    	      	// get all cimgs
16                var all_cimg = document.querySelectorAll("[id^='cimg_']");
17                // Convert NodeList to an array
18                var cimgs = Array.from(all_cimg);
19                // alert("test");
20                
21                for (i = 0; i < cimgs.length; i++) {
22                    var cimg_id = cimgs[i].id;
23                    var cvh_id = 'cvh_' + cimg_id.replace("cimg_", "");
24                    // set values
25                    document.getElementById(cvh_id).value = d.captcha_verification_hash;
26                    document.getElementById(cimg_id).style.backgroundImage = 'url(' + d.captcha_image_url + '?w=55&amp;h=22&amp;s=11' + ')';
27                }
28	      	}
29   		}
30	};
31	xhr.send(kP);
32}