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Build Status Bower Version npm Version Nuget Version lawgr

Simple JavaScript logging library. Supports logging to local console as well as a remote endpoint.



Lawgr has the concept of logging targets, a target being a function which is be called when any of the logging functions are called. The default configuration includes a target called local, which renders messages to the local console.

A remote target is also provided for sending log messages to a remote endpoint. To make use of it you can reconfigure the targets property as follows:

log.config.targets = [ log.defaults.targets.local, log.defaults.targets.remote ];

The log.defaults.targets.remote target will post log messages to /logs/ with a body like this:

	level: "error",
	message: "Oh noes!",
	sender: "some-app",
	stack: [{
		context: [
			"var someFuncName = function() {",
			"    throw new Error('Oh Noes');",
		func: "someFuncName",
		line: 2,
		column: 12,
		url: ""
	url: "/"
	useragent: "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/35.0.1916.153 Safari/537.36"

The sender and destination URL are configured as follows:

log.config.sender = 'some-app';
log.config.url = '/logs/';

The stack property is only included if available. Stack traces are obtained through TraceKit.

You can also implement your own target(s) by providing a function with the following signature:

function (level, message, stack)

level will be one of debug, info, warning, error or critical. message is the log message. stack corresponds to the stack property in the example above.


The API for logging messages is simple:

log.debug('This is a debug thing');'This is an informational thing');
log.warning('This is a warning thing');
log.error('This is an error thing');
log.critical('This is a critical thing');

// log.error and log.critical also accept an Error object
var error = new Error('Oh noes!');


Unhandled errors (window.onerror) are automatically caught and logged as an error. However, once an error hits window.onerror, the stack trace is limited to a single frame. For better stack traces, use try-catch blocks within your code:

try {
catch (e) {

When throwing errors, create an instance of Error rather than using a string:

throw new Error('Oh noes!');


Bower Bower Version

bower install lawgr

npm npm Version npm Downloads

npm install lawgr

NuGet Nuget Version Nuget Downloads

Install-Package lawgr.js


Prior to publishing a new version of the package, you must run the following commands to configure your NuGet and npm credentials. You should only need to do this once.

npm adduser

Once you have entered your credentials, you can publish to npm and NuGet by running one of the following tasks:

grunt publish

Increments patch version in package.json, publishes to npm and NuGet. This is short-hand for grunt publish:patch.

grunt publish:minor

As before, but bumps minor version.

grunt publish:major

As before, but bumps major version.

The publish task will create an appropriate semver tag which Bower will detect as a new version.


Simple JavaScript logging library.



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