Debug Console JS

Turns javascript console on and off, sets console logging level threshold, and automatically skips console methods that are not available in the current browser.

About

This simple library was made to highlight javascript console role as a debugging tool and pursuits the following goals:

• No output from console, unless debug mode is explicitly turned on
• console calls don't cause js exceptions if they are not supported, even if debug mode is on
• console output could be easily turned on and fine tuned, i.e. allowing only console.warn logs or higher.
• Very small footprint, doesn't require any existing code modifications to use and won't break any code when uninstalled

Usage

When console.js is included on a page:

<script src="console.js"></script>

all console calls will be automatically ignored, so no output from console in browsers that support it, and no exceptions in browsers that don't.

Console output is controlled through global var DEBUG, which could take the following values:

• <true|"on"> - console calls are enabled, calls not supported by a browser are silently ignored
• <false|"off"> - all console calls are silently ignored
• <"log"|"debug"|"info"|"warn"|"error"> - all console calls are disabled except logging calls with a logging level that is equal or greater than the provided threshold

Often it is needed to temporary enable console for a quick debug, you can do so without even modifying the DEBUG var value by appending #debug URL hash or debug URL parameter to the current page URL, for example:

http://example.com#debug (would require manual page refresh as adding hash doesn't reload the page)
http://example.com?debug

URL parameter is equal to setting DEBUG=true and overrides any existing DEBUG values.

Examples

DEBUG mode is off (default), all console calls are ignored:

<script src="console.js"></script>
<script>
	console.time("timer");		//ignored
	console.dir("DIR");		//ignored
	console.log("LOG");		//ignored
	console.warn("WARN");		//ignored
	console.log("ERROR");		//ignored
	console.timeEnd("timer");	//ignored
</script>

DEBUG mode is on, all supported console calls are allowed:

<script>
	DEBUG = true;
</script>
<script src="console.js"></script>
<script>
	console.time("timer");		//allowed
	console.dir("DIR");		//allowed
	console.log("LOG");		//allowed
	console.warn("WARN");		//allowed
	console.log("ERROR");		//allowed
	console.timeEnd("timer");	//allowed
</script>

DEBUG mode is on with the threshold, all console calls are disabled except logging calls with the logging level that is equal or greater than warn level:

<script>
	DEBUG = "warn";
</script>
<script src="console.js"></script>
<script>
	console.time("timer");		//ignored
	console.dir("DIR");		//ignored
	console.log("LOG");		//ignored
	console.warn("WARN");		//allowed
	console.log("ERROR");		//allowed
	console.timeEnd("timer");	//ignored
</script>