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An easy-to-use but powerful node.js command-line logger


Loggie is a lovely logger for node.js which is SMART, SMALL, and EASY-TO-USE.

Loggie has few options, which makes it work at your will.


npm install loggie --save


For most cases, you could use loggie immediately with no extra configurations

var loggie = require('loggie');
logger = loggie();'{{cyan install}}', 'loggie'); // will print a cyan 'install', space, and 'loggie'. 

You could use typo template here to format your output.

There're several built-in log methods.

Built-in log methods

Method) Enabled By default) Binded Argv) Leading String)
verbose no --verbose 'VERB ' in gray
debug no --debug '[D] ' in magenta
error yes bold 'ERR! ' in red
warn yes 'WARN ' in yellow
info yes (nothing)
logger.debug('blah-blah'); // will do nothing 

Because 'debug' is not enabled by default.

But if you start your app with '--debug' option, logger.debug will be activated. Or, you could add 'debug' into log levels in loggie options or with logger.addLevel method.



Will create a new loggie instance



options.level is just the loggie methods you want to activate. For example:

var logger = loggie({
    level: 'info, error' // can also be ['info', 'error'] 

Then, logger.warn('blah-blah') will be deactivated and do nothing.

If set to '*', Loggie will enable all log methods.



Default to true

If set to true, Loggie will detect 'exit' event of process, if process exited without logger.end() method, it will be considered as a failure.

Best practices

var logger = loggie({
    level: process.env['MY_LOG_LEVEL'] || 
        // log level for production 
        'info, error, warn'

And your environment variables (maybe on Mac OS) could be:

# file: ~/.profile
export MY_LOG_LEVEL=debug,info,error,warn

So, you can use local settings for debugging and development, and will never worry about the possible forgetness of changing debug configurations to production.

Define custom log methods

    detail: {
        template: '{{cyan|bold|underline Detail}} {{arguments}}', // typo template 
        argv: '--detail'

Then, we defined a log method logger.detail():

logger.detail('a'); // might print a bold cyan 'detail' with a underline, a whitespace, and an 'a' 

By default, logger.detail() will do nothing because it is not in the log level list(options.level), but it will be activated if your app is started with '--detail' argument.

You can also use logger.addLevel('detail') to add 'detail' to level list.


.register(name, setting)

Define your own log method. You can also use this method to override existing log methods.



The name of the log method you want. If you register() with name = 'verbose', there will be a logger.verbose() method.



A typo syntax template.

There are several built-in template parameters to be used:

'arguments': arguments joined by a single whitespace (' ')

number: such as '0', the argument at index 0

If you use the template, all arguments will be stringified


logger.register('verbose', {
    template: '{{gray verbose}} {{0}} {{arguments}}'
    // notice that the first argument will be duplicated once 
logger.verbose('mylabel', 'blah', new Error('error:blah-blah'));

Will print: verbose(gray) mylabel mylabel blah error:blah-blah



The log method.

Notice that if setting.template is defined, setting.fn will be overridden.