Lightweight logging library for NodeJS with support of facilities and multiple transports.
var logger = require("meta-logger");
//Setup targets
logger.toConsole({
level: "debug",
timestamp: true,
colorize: true
}).toFile("demo.log", {
level: "info",
timestamp: true,
facilities: [ "test" ]
}).toJsonFile("demo.json", {
level: "warn"
});
//Logging without specifying facility
logger.log("info", "Hello %s", "world");
logger.debug("Hello %s", "debug");
logger.info("Hello %s", "info");
logger.warn("Hello %s", "warn");
logger.error("Hello %s", "error");
//Create facility shorthand
var facilityLogger = logger.facility("test");
//Log with facility prefix
facilityLogger.log("info", "Hello %s", "world");
facilityLogger.debug("Hello %s", "debug");
facilityLogger.info("Hello %s", "info");
facilityLogger.warn("Hello %s", "warn");
facilityLogger.error("Hello %s", "error");Note: console target is set by default.
Prints log messages to stdout (console).
logger.toConsole({
level: "debug",
facilities: [...], //or null to accept all facilities
timestamp: true,
colorize: true,
colors: {
debug: logger.colors.cyan,
info: logger.colors.white,
warn: logger.colors.yellow,
error: logger.colors.red
}
});Method toConsole overrides previous console target settings. You can use more console targets (for multiple configurations):
logger.to(new Logger.ConsoleTarget({
///... options ...
}));
Append log messages to specified file.
Message is formatted same way as to console.
File target can be set for multiple files with different configurations.
logger.toFile(filename, {
level: "debug",
facilities: [...], //or null to accept all facilities
timestamp: true
}).toFile(anotherFilename, {
level: "error",
timestamp: true,
//...
});Append log messages to specified file in JSON format.
logger.toJsonFile(filename, {
level: "debug",
facilities: [...], //or null to accept all facilities
timestamp: true
});Log file has following format:
{},
{"timestamp":"2015-06-04T21:20:54.627Z","level":"warn","facility":null,"msg":["Hello %s","warn"]},
{"timestamp":"2015-06-04T21:20:54.629Z","level":"error","facility":"test","msg":["Hello %s","error"]}
...
Custom target is defined by instance of simple object which implements log method and registered to logger via to method.
Following example shows how to define custom target:
var util = require("util");
var MyTarget = function(options){
options = options || {};
this.prefix = options.prefix || "";
};
MyTarget.prototype.log = function(level, facility, args){
console.log(level, facility, this.prefix, util.format.apply(this, args));
};
logger.to(new MyTarget({
prefix: "my-target"
}));Following example shows how to inherit BaseTarget:
var MyTarget = function(options){
options = options || {};
this.prefix = options.prefix || "";
logger.BaseTarget.call(this, options);
};
util.inherits(MyTarget, logger.BaseTarget);
MyLogger.prototype.write = function(level, facility, msg){
console.log(level, facility, this.prefix, msg.join(" "));
};Logging levels can be set by modifying logger.levels property.
logger.levels = {
custom: 4,
debug: 3,
info: 2,
warn: 1,
error: 0
};logger = {
//Colors library for console coloring
colors: require("colors"),
//Logging levels
levels: {
debug: 3,
info: 2,
warn: 1,
error: 0
},
//Object contains registered targets
targets: {},
//Logging functions
log: function(level, args...),
debug: function(args...),
info: function(args...),
warn: function(args...),
error: function(args...),
//Facility shorthand
facility: function(name){
return {
log: function(level, args...),
debug: function(args...),
info: function(args...),
warn: function(args...),
error: function(args...)
};
},
//Target shorthands
to: function(name, targetObject),
toConsole: function(options),
toFile: function(filename, options),
toJsonFile: function(filename, options),
//Target constructors
BaseTarget: function(options),
ConsoleTarget: function(options),
FileTarget: function(filename, options),
JsonFileTarget: function(filename, options)
};This library is published under MIT license.
Copyright (c) 2015 Jiri Hybek, [email protected]