Changes in SharePoint Online (Office 365)

Question

I have an idea to solve a problem by adding jQuery/javascript to a aspx page (in this case the DispForm.aspx) But I thought I've heard that SharePoint Online installs automatically updates. Can this updates have an impact on the jQuery I've wrote? Like changing client id's or other. And how many times a year are there updates? Any thoughts about this, why we shouldn't do this?

Answer 1

No, the automatic updates will not affect your changes.

Whenever you customize a default SharePoint page (DispForm.aspx in your case), it becomes unghosted and the changes you made to the page are stored in the Content database. Now whenever you make a request to that page, the data from both the file system (original page) and the content database (custom changes) is fetched and shown.

Also as a result of unghosting, if you modify any particular list's DispForm.aspx, then the changes are reflected only on that list and not every other list's DispForm.aspx.

Answer 2

This does not directly answer your question, but:
If you use <CustomAction Location="ScriptLink" /> in a Module and deploy that and try writing selectors that don't depend on ID you should be safe.