To open the Web Console:
- either select "Web Console" from the Web Developer submenu in the Firefox Menu (or Tools menu if you display the menu bar or are on Mac OS X)
- or press the CtrlShiftK (CommandOptionK on OS X) keyboard shortcut.
The Toolbox will appear at the bottom of the browser window, with the Web Console activated (it's just called "Console" in the DevTools toolbar):
The Web Console's interface is split into three horizontal sections:
- Toolbar: along the top is a toolbar containing buttons with labels like "Net", "CSS", and "JS". This toolbar is used to filter which messages are displayed
- Command Line: along the bottom is a command line that you can use to enter JavaScript expressions
- Message Display Pane: in between the toolbar and the command line, and occupying most of the window, is the space in which the Web Console displays messages