This somewhat complicated script demonstrates getting a 2D drawing from
ChemSpider based on a chemical identifier through a multi-step process
using JavaScript and a server-side proxy. It uses advanced features of
the core JSmol library to accomplish this, though it does not use the JSmol applet itself.

Press the "test" button to evaluate the JavaScript in the textarea below.
Feel free to modify the JavaScript and press test again.

// We go from identifier -(CIR)-> InChI -(CS)-> csid -(CS)-> image.

var id = prompt("Enter a compound identifier", "tylenol");
var inchi = Jmol._getFileData("https://cactus.nci.nih.gov/chemical/structure/"+id+"/stdinchi");

alert("InChI is \n\n" + inchi + "\n\n")

// This next step, retrieving the ChemSpider id, requires a server-side proxy
// because ChemSpider does not allow direct AJAX access.
// This is our server-side proxy for accessing ChemSpider.
Jmol._serverUrl = "https://chemapps.stolaf.edu/jmol/jsmol/php/jsmol.php";

var csURL = "https://www.chemspider.com/InChI.asmx/InChIToCSID?inchi="+encodeURIComponent(inchi);
var csRet = Jmol._getFileData(csURL);
alert("ChemSpider returned \n\n" +  csRet + "\n\n")
var csXML = $(csRet);
var csid = parseInt(csXML[2] && csXML[2].innerHTML);

alert("ChemSpider ID is " +  csid);

// we check here to see that both getting the InChI and getting the ChemSpider ID were successful

var url = "http://chemspider.com/image/" + csid;
$("#url").html(url);

if (isNaN(csid))
  alert((inchi ? "no ChemSpider ID was available " + csRet : "No InChI was found") + " for " + id);
else
  $("#image").attr("src",url);

url:
image: