Sometimes you need to persist console information between page loads. Sometimes we need this for reference or perhaps to view any logs that occur on click or unload.
In Chrome, right click in the console to reveal a menu with "Preserve Log upon Navigation" as an option. Selecting this will keep your console content.
Firefox will persist console content by default. You can clear the console log by clicking the 'clear' button in the top right or opening and closing the tools.
In Firebug, there’s an obvious button for persisting console content directly above the console.
Opera will persist console content by default. You can clear the console log by right clicking and selecting "Clear console" or by opening and closing the tools.