Got weird user complaint but can't find the problem?

Dunno?
- dunno what user did, where clicked, on which pages?
- dunno where he was 5 sec ago? maybe JS errors 10 sec ago?
- dunno the root cause?
Dunno gives you a clear steps to reproduce.
Do know!
Add script <script src="dunno.js"></script>
or require for browserify
npm install dunno;
var dunno = require('dunno')
Start tracking asap
dunno.start();
window.onerror = function() {
console.log(dunno.tell());
};
User jumps between pages, does weird stuff, gets an error - you get repro steps.
error: Uncaught ReferenceError: invoiceState is not defined
url: /sets/55b941e794a73c03008db78c ~
click: <a cl="set-tab hidden"></a> ~
click: <a cl="set-tab ">Coco</a> ~
url: /games ~
click: <div id="set-header">Create</a> ~
url: /sets/55b941e794a73c03008db78c/55bbd7c2461ab603007d1648a ~
error: Uncaught TypeError: saveInvoice is not a function
away ~
url: /all?cachereset=100023402
Just post dunno.tell()
to LogEntries or whatever you use. Now you know!