@rearc/noop-log

Simple JSON logger for Noop components

Usage no npm install needed!

<script type="module">
  import rearcNoopLog from 'https://cdn.skypack.dev/@rearc/noop-log';
</script>

README

noop-log

JS logging library for Noop components following Noop standard JSON format. The library is very simple and allows mixed types to be output easily (strings, objects, and Errors). This library is hosted publicly on NPM.

Quickstart

npm install @rearc/noop-log --save

const log = require('@rearc/noop-log')
log.info('something happened', 'over here', {id: 42}, new Error('damn'))

This outputs a single line JSON object with all the arguments above like:

{"level":"info","date":"2018-03-16T19:20:13.951Z","id":42,"inner":{"message":"damn","stack":"Error: damn\n    at repl:1:55\n    at sigintHandlersWrap (vm.js:22:35)\n    at sigintHandlersWrap (vm.js:73:12)\n    at ContextifyScript.Scr
ipt.runInThisContext (vm.js:21:12)\n    at REPLServer.defaultEval (repl.js:340:29)\n    at bound (domain.js:280:14)\n    at REPLServer.runBound [as eval] (domain.js:293:12)\n    at REPLServer.<anonymous> (repl.js:538:10)\n    at emit
One (events.js:101:20)\n    at REPLServer.emit (events.js:188:7)"},"msg":"something happened over here"}

Log Levels

The log output level defaults to info but can be configured through the LOG_LEVEL environment variable. The available levels in order of severity are:

  • log.debug()
  • log.info()
  • log.warn()
  • log.error()
  • log.fatal()

Argument Types

All logging functions accept unlimited arguments of the string, object, and Error types.

  • string all strings provided as arguments will be concatenated (in the order provided) into the msg property of the output event
  • object all object types provided as arguments result in their properties being added to the output event. log.info({id: 42, name: 'foo'}) will result in the output event having the id and name properties applied. This also includes deep objects.
  • Error all JS Error object types will be have their details added to the inner property of the output event. This fits the common case of recording the details of a lower level error along with your own message.