Entering raw HTML in editors
From Joomla! Documentation
If you want to enter raw HTML in a Joomla! editor field, you may encounter problems such as tags and attributes disappearing after you save the item you are editing. This is usually caused by a filtering mechanism; either your editor's or Joomla!'s.
Global Text Editor Configuration
On the Administrator panel, take the following steps to disable filtering:
Disable Your Editor
Since each editor has its own filtering mechanism and it is not always possible to turn it off, disabling your editor is the easiest way of eliminating it as a possible source of the problem. Open your user configuration from the Administrator → Users menu. Select the Basic Settings tab. Change the Editor to Editor - None. Select Save & Close.
Disable Joomla's Filtering
Open the Global Configuration from the Site menu and go to the Text Filters tab. Set the Filter Type to No Filtering for the user group that you are in - Administrator, Super Users, or both (this is site-dependent). Caution: Do not use the No Filtering setting for user groups that are not fully trusted – that would introduce a sizeable security risk.
You should be able to enter raw HTML in any editor field now. You may try to re-enable your editor to see whether it influences the process. If the editor does mangle the HTML you are trying to enter, consult its documentation to see if there is a way to disable its filtering.
When the Text Editor in Use is TinyMCE
You may be able to make some adjustments to it and keep your WYSIWYG editor.
- Go to Administrator → Extensions → Plugins.
- Search for TinyMCE and open it for editing.
- Choose the Set 0 tab or whichever set has Super-Users or your desired user group.
- Scroll down to Prohibited Elements.
- Remove iframe (with its leading comma, if present) or whatever text you need to stop being prohibited.
- Select Save & Close.
Always be wary of doing this. Users may intentionally or unintentionally (hacked accounts) post something malicious which could affect your guests.