node-logger

Simple yet powerful logger. Logs to file and/or console, different loglevels, logs date, logs origin file, logs errors with stack trace, ...

Installation

npm install HardwareProjects/node-logger --save

To use the logger, copy the node-logger.json file to the base directory of your node app. Do not rename the file.

Usage

let log = Logger.createFromConfigFile();
let isInfo = log.isInfoOrVerboser();

isInfo && log.info("Checking isInfo prevents expensive argument evaluation if not needed. Note that the filename where the logger was created is included as a tag. %j", util.inspect(log));
// 2016-05-01T15:35:19.997Z INFO  [readme-examples-text.js] - Checking isInfo prevents expensive argument evaluation if not needed. Note that the filename where the logger was created is included as a tag. "Logger <inspect results>"}

log.info2(["functional_warning"], "This message includes a tag, so it can be easily filtered.\n Note that there is always exactly one output line per message for JSON format but not for text format.");
// 2016-05-01T15:19:03.443Z INFO  [readme-examples-text.js, functional_warning] - This message includes a tag, so it can be easily filtered.
// Note that there is always exactly one output line per message for JSON format but not for text format.

let touchFeatureLog = Logger.createFromConfigFile(["touch_feature"]);
touchFeatureLog.error(new Error("Messages form this logger will have the tags specified during creation. Note that all log-functions return promises."))
    .then(() => process.exit());
// 2016-05-01T15:20:17.442Z ERROR [readme-examples-text.js, touch_feature] - [Error: Messages form this logger will have the tags specified during creation. Note that all log-functions return promises.] STACK: <full stack trace>


// Switch to JSON output format.
log.logFunctions = [Logger.LogFunction.defaultJson];

isInfo && log.info("Checking isInfo prevents expensive argument evaluation if not needed. Note that the filename where the logger was created is included as a tag. %j", util.inspect(log));
// {"isoDate":"2016-05-01T15:49:05.061Z","level":"INFO","tags":["readme-examples-text.js"],"text":"Checking isInfo prevents expensive argument evaluation if not needed. Note that the filename where the logger was created is included as a tag. \"Logger <inspect result>"}

log.info2(["functional_warning"], "This message includes a tag, so it can be easily filtered.\n Note that there is always exactly one output line per message for JSON format but not for text format.");
// {"isoDate":"2016-05-01T15:49:05.062Z","level":"INFO","tags":["readme-examples-text.js","functional_warning"],"text":"This message includes a tag, so it can be easily filtered.\n Note that there is always exactly one output line per message."}

let touchFeatureLog = Logger.createFromConfigFile(["touch_feature"]);
touchFeatureLog.error(new Error("Messages form this logger will have the tags specified during creation. Note that all log-functions return promises."))
    .then(() => process.exit());
// {"isoDate":"2016-05-01T15:49:05.062Z","level":"ERROR","tags":["readme-examples-text.js","touch_feature"],"text":"[Error: Messages form this logger will have the tags specified during creation. Note that all log-functions return promises.]","stack":"Error: Messages form this logger will have the tags specified during creation. Note that all log-functions return promises.\n    at <full stack trace>"}