A very simple logger with levels, thats it, no frills.
$ npm install --save loggerr
var Loggerr = require('loggerr');
var log = new Loggerr();
log.error(new Error('My error message'));
/*
output: Thu Apr 16 2015 22:05:27 GMT-0500 (CDT) [error] - {"msg":"Error: My error message\n<STACK TRACE>"}
*/
log.info('Something happened', {
foo: 'info about what happened'
});
/*
output: Thu Apr 16 2015 22:05:27 GMT-0500 (CDT) [info] - {"msg":"Something happened","foo":"info about what happened"}
*/Loggerr supports log levels. Each log level can be directed to a different output stream or disabled entirely. The supported levels are as follows:
- Emergency
- Alert
- Critical
- Error
- Warning (default)
- Notice
- Info
- Debug
Constants are available for setting and referencing the levels and their streams. These constants are the all uppercase version of the level. Here is an example of setting the log level:
var logger = new Loggerr({
level: Loggerr.DEBUG
});
logger.debug('Foo');
/*
output: Thu Apr 16 2015 22:05:27 GMT-0500 (CDT) [debug] - {"msg":"Foo"}
*/Loggerr supports formatting via formatter functions. The default formatter outputs a timestamp, the log level and the messages formatted as json. But you can provide a custom formatter function with the formatter options. Formatter functions take three parameters: date, level, data. Say we want to output the log message with a color based on the level:
var Loggerr = require('loggerr'),
chalk = require('chalk');
var logger = new Loggerr({
formatter: function(date, level, data) {
var color;
switch(Loggerr.levels.indexOf(level)) {
case Loggerr.EMERGENCY:
case Loggerr.ALERT:
case Loggerr.CRITICAL:
case Loggerr.ERROR:
color = chalk.red;
break;
case Loggerr.WARNING:
case Loggerr.NOTICE:
color = chalk.yellow;
break;
case Loggerr.INFO:
case Loggerr.DEBUG:
color = chalk.white;
break;
}
return color(data.msg);
}
});There are two built in formatters:
default: Outputs date, level and jsoncli: Outputs just the message and json data, colorized and formatted
To use the cli formatter just require it and pass the formatter options:
var logger = new Loggerr({
formatter: require('loggerr/formatters/cli')
});You can output each level to it's own stream. The method is simple, just pass an array of streams corresponding to each level as the streams option. The simplest way is to just map over Loggerr.levels, this is how we set the defaults:
new Loggerr({
streams: Loggerr.levels.map(function(level, i) {
return i > Loggerr.WARNING ? process.stdin : process.stderr;
})
});The most useful reason to specify an output stream to to redirect logs to files. Here is an example of how to do that:
var logfile = fs.createWriteStream('./logs/stdout.log', {
flags: 'a',
encoding: 'utf8'
});
new Loggerr({
streams: Loggerr.levels.map(function() {
return logfile;
})
});
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