HTML Panel

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Revision as of 09:24, 27 May 2010 by Johnjbarton (Talk | contribs) (Style)

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HTML Panel

The HTML panel displays the generated HTML/XML of the currently opened page. It differs from the normal source code view, because it also displays all manipulations on the DOM tree. On the right side it shows the CSS styles defined for the currently selected tag, the computed styles for it, layout information and the DOM variables assigned to it in different tabs.

Options Mini Menu

The options menu contains an option for toggling the display of full text contents or a shortened version, for white spaces, for comments and basic entities. Functional options include highlighting changes to the DOM tree, expanding the changes and scrolling them into view. Besides that you can choose, if you want the box model to be shaded or just marked by a frame around it when hovering nodes inside the tree structure and have an option to display a quick info box inside the page, that shows the most important information about a node when hovering it inside the structure.

Panel Toolbar

Break On Mutate

The "Break On Mutate" button gives you the possibility to stop JavaScript execution when any mutation of the HTML via the script occurs. If a mutation occurs, Firebug halts the script execution and jumps to the Script Panel to the line where the change happened.


Enabling the "Edit" mode by hitting the appropriate button lets you edit the HTML directly. Therefore it opens a text editor, which is filled with the node and its contents you currently had selected in the formatted (tree view) mode. After turning the edit mode off again the display switches back to the formatted mode, which now displays the changes made to the source code.

Element Path

Inside the panel menu there is a list of nodes, starting with the currently selected node and going up the element structure up to the root node of the document. The list looks like what some Web sites call a "breadcrumb" list. Hovering one of the nodes inside the list shows a highlighting box around the element inside the page and clicking on it selects the node inside the tree structure of the HTML panel. The context menu of each item in the list offers thereby the same options as the node's context menu inside the tree structure.

Node View

The body of the panel represents the document nodes of the page converted back into a source-like view. Note that this view is created from the live document: this is not a source view. The view can be based on any kind of markup, e.g. HTML, XML, or SVG graphics. Right-clicking on a node opens a context menu with options for copying the contents or the path as XPath or CSS selector path. It offers an option for logging events based on the node and it can be scrolled into view. You can jump to the DOM panel to inspect the element, edit the HTML content of the node, add attributes or delete the node. Beyond that you have the possibility to enable different "Break On..." features for the specified node.

Side Panels

Besides node manipulation the HTML panel also offers a lot of information around the selected elements. This information appears in the side panels on the right, selected by another set of tabs.


Inside the style tab you can see the CSS styles, that are currently assigned to the selected node. It also offers you similar possibilities of CSS manipulation like the CSS panel. The difference between them is organizational. Inside the CSS tab just the styles assigned to the selected node are shown (which can lie in different files); Inside the CSS panel all styles defined in one CSS file is shown. Furthermore the CSS tab shows you the cascading info, meaning styles, that are overwritten by other style definitions will be shown lined-through.

The Style side panel options menu includes options for:

  • showing the user agent's CSS styles,
  • expanding shorthand CSS properties,
  • and whether :active and :hover styles shall be listed inside the shown styles.


The computed tab shows all style values the browser calculated for display while interpreting the given CSS information. So it shows the actual displayed styles. The options menu offers the possibility to reload the displayed information.


The layout tab gives a quick overview over the box model values. But it also offers an easy way to change the values by simply clicking on one of them. When hovering over different parts of the box model, the element inside the page highlights, the borders of the hovered part has line guides and a horizontal and vertical rules for measurement. In the options menu you can toggle the display of the line guides and rules.


You can see information about the DOM according to the selected node inside the DOM tab. This tab offers the full functionality of the DOM Panel. This also includes its options menu.