I have used Penzu as my main journal app for many years. Recently when Apple launched its Journal app I have been looking at it and other competitors. Then I realized that I am not able to get my own data from Penzu. There is no reasonable Export function.

So I found my own way to get my journal data. I could name this blog post to something like “How to export the unexportable”, or “How to intercept XHR requests in Puppeteer”, but my case is about Penzu, so I’ll stick to this particular title.

$.ajax is great, it hides much of the complexity. But sometimes we need to work with “raw” javascript :) So let’s look behind the scenes. The XMLHttpRequest (or just XHR) is used to open a connection to a server without a page reload. Internet Explorer calls it ActiveXObject and it differs in IE versions. Wikipedia article gives a good example how to create one constructor for all browsers: [sourcecode language=“javascript”]if (typeof XMLHttpRequest == “undefined”) XMLHttpRequest = function () { try { return new ActiveXObject(“Msxml2.XMLHTTP.6.0”); } catch (e) {} try { return new ActiveXObject(“Msxml2.XMLHTTP.3.0”); } catch (e) {} try { return new ActiveXObject(“Microsoft.XMLHTTP”); } catch (e) {} //Microsoft.XMLHTTP points to Msxml2.XMLHTTP and is redundant throw new Error(“This browser does not support XMLHttpRequest.”); };[/sourcecode] The remainder is more or less the same among the browsers. We open a connection defining the HTTP verb, URI and async mode (true or false): [sourcecode language=“javascript”]var xhr = new XMLHttpRequest(); xhr.open(“GET”, “/_vti_bin/listdata.svc”, true); xhr.onreadystatechange = onStateChange; xhr.send(null);[/sourcecode] Pay attention to onreadystatechange (only lower case letters). If we choose async=false, the UI waits for the response which is not so kind to users, but maybe it is easier to write a program. Well, there is actually no option but to have async=true. To provide the callback for success and error we can write the responding function onreadystatechange. This function will be called every time the state is changed. There are 5 states:

In one of my previous posts I showed how to retrieve data from listdata.svc with jQuery $.getJSON method. Getting data is very simple, listdata.svc provides a powerful restful interface with filtering, expanding and other features. Read the best and short introduction to listdata.svc by Suneet Sharma or a more detailed and technical article about filters, functions and operators by Mike Flasko at Microsoft with short examples here. Now back to listdata.svc in the SharePoint environment. Corey Roth provides a good images and sample results. For REST the “http verbs” are very important: GET, POST, PUT, DELETE.. SharePoint RESTful interface defines these verbs like that: