An extension that has a security issue or a flaw because of its poor coding can be said as a vulnerable joomla extension.

To protect your site affecting from the vulnerable issues follow the below steps:

I wanted paging for showing datalist items in pages.for
that i used pageddatasource.it's necessary very much.
following codes show how to add paging for datalist items -

how to insert data in specific joomla table? this way -

if you wanted to use jquery like for showing/hiding panel
when button clicked inside datalist itemtemplate then you
experienced that the action is repeated per item.

you may have seen input textbox becomes wider
dynamically in some websites when mouse cursor is
placed on it(in focus) to take some user input.It's
attractive to see and in this way it makes spaces
for larger input.

Facebook dialog is a great way to post to a profile/page wall.
There are many dialogs in faceook developer doc page -
https://developers.facebook.com/docs/dialogs/

It's a very common to get joomla module's setting parameters in
code to process the module.It's easy but sometimes things
become complicated if you don't find the right way to do
that.