[main] pass input data to output

Resolves #303

lib/main.js

@@ -659,7 +659,7 @@ function StartQueue() {
   //  and set the content with the proper delimiters
   //
   var item = queue.shift();
-  data = item[0]; callback = item[1];
+  data = item[0]; callback = item[1]; originalData = item[2];
   content.innerHTML = "";
   MathJax.HTML.addElement(content,"script",{type: "math/"+TYPES[data.format]},[data.math]);
   html.setAttribute("xmlns:"+data.xmlns,"http://www.w3.org/1998/Math/MathML");
@@ -773,7 +773,7 @@ function ReturnResult(result) {
     state.n = GLYPH.n;
     state.ID = ID;
   }
-  callback(result, data);
+  callback(result, originalData);
   serverState = STATE.READY;
   StartQueue();
 }
@@ -835,7 +835,7 @@ exports.typeset = function (data,callback) {
   }}
   if (data.state) {options.state = data.state}
   if (!TYPES[options.format]) {ReportError("Unknown format: "+options.format,callback); return}
-  queue.push([options,callback]);
+  queue.push([options,callback,Object.assign({},data)]);
   if (serverState == STATE.STOPPED) {RestartMathJax()}
   if (serverState == STATE.READY) StartQueue();
 }

test/pass_data.js

@@ -0,0 +1,16 @@
+var tape = require('tape');
+var mjAPI = require("../lib/main.js");
+
+tape('Passing data along', function(t) {
+    t.plan(1);
+    mjAPI.start();
+    var tex = 'x';
+    mjAPI.typeset({
+        math: tex,
+        format: "TeX",
+        css: true,
+        something: 'expected',
+    }, function(data, input) {
+        t.equal(input.something, 'expected', 'Data was passed along to output');
+    });
+});