JavaScriptConsole

Displays an interactive list of the properties of the specified JavaScript object. The output is presented as a hierarchical listing with disclosure triangles that let you see the contents of child objects.

MDN

Outputs an error message. You may use string substitution and additional arguments with this method. See Using string substitutions.

MDN

Outputs an informational message to the Web Console. In Firefox, a small "i" icon is displayed next to these items in the Web Console's log.

MDN

For general output of logging information. You may use string substitution and additional arguments with this method. See Using string substitutions.

MDN

Outputs a warning message. You may use string substitution and additional arguments with this method. See Using string substitutions.

MDN