Hello

I am new to java. I downloaded a code that I want to use for a project that I am doing. Part of the code has a java script that I studied but could not understand it.

Code:
uint16_t plen;
 if (random_arr[random_arr_index]==0){ random_arr[random_arr_index]=43; // we can not use 0 } plen=http200okjs(0); plen=fill_tcp_data_p(buf,plen,PSTR("function pad(s){if(s.length<2){return('0'+s)}return(s)}\n")); // the function cy makes it impossible to re-use the same URL-get more than 60sec later 
plen=fill_tcp_data_p(buf,plen,PSTR("function cr(f){ c=")); itoa(random_arr[random_arr_index],gStrbuf,10); // convert integer to string plen=fill_tcp_data(buf,plen,gStrbuf); plen=fill_tcp_data_p(buf,plen,PSTR(";r='")); // the first digit in the return value is the random_arr_index itoa(random_arr_index,gStrbuf,10); // convert integer to string plen=fill_tcp_data(buf,plen,gStrbuf); plen=fill_tcp_data_p(buf,plen,PSTR("';s=f.value;i=s.length;j=0;while(j<i){r+=pad(((0xff & s.charCodeAt(j))^c).toString(16));j++} f.value='';return(r)}\n")); plen=fill_tcp_data_p(buf,plen,PSTR("function ni(d,n,v){var i=document.createElement('input');i.setAttribute('type','hidden'); i.setAttribute('name',n);i.setAttribute('value',v);d.insertBefore(i,d.firstChild)}\n")); plen=fill_tcp_data_p(buf,plen,PSTR("function cy(d){d.y.value=cr(d.c)}\n")); plen=fill_tcp_data_p(buf,plen,PSTR("function csm(d){ni(d,'y',cr(d.c));ni(d,'z',cr(d.n))}\n")); plen=fill_tcp_data_p(buf,plen,PSTR("function csp(d){ni(d,'y',cr(d.c));ni(d,'z1',cr(d.c1));ni(d,'z2',cr(d.c2))}\n")); return(plen);
There are not much comments on this part and with the knowledge that I have on java script, I could not figure out what the code is doing. Can someone help. I would also like to know of any links that clearly explain such codes