In the previous versions of LibreOffice, one could insert script into an odt from "insert" menu.
According to official answer this feature was removed: https://ask.libreoffice.org/en/question/67576/menu-insert-script-removed/
How am I then supposed to insert script? What is "Writer HTML", which this answer is suggesting? I can't find a word about it anywhere else.
Am I forced to install earlier versions of LibreOffice just for this feature if I want to avoid digging through massive XMLs?
Also, can anyone explain the reason of that move (removing existing, convenient feature from the product)?
To create an HTML document in Writer (meant by "Writer HTML"), go to File -> New -> HTML Document, and then it will be possible to insert a script. Or, it sounds like you may want File -> New -> XML Form Document instead.
It looks to me like Insert -> Script is useful only for adding Javascript or similar to a document, which seems appropriate for an HTML document or forms. So the new change makes sense to me.
To write a Javascript macro, put the code in a text file under the LibreOffice user directory, as described here.
EDIT:
From the comment below, it sounds like you are inserting a directive for use with JODReports. Could you do the following instead:
Insert a FreeMarker directive in OpenOffice.org Writer from the menu Insert / > Fields / Other... (or just press Ctrl+F2), then click on the Functions tab and > select Input field. Change the field Reference to JOOScript and in the > following field Content enter the directive (e.g. "[#assign title='Mr.']").
Note: Apache OpenOffice still has Insert -> Script.