Logging Helper Module

Module to standardize logging output.

Why?

I don’t like using console.log everywhere in my code. So this module allows me to standardize log statements with certain format.

Notable Features

• Log levels
• Output by log levels
• Standardized log structure that includes (but not limited to) app name, module name, function name, and other information
• High-order functions to wrap module name and function name

Log Entry

export interface LogEntry {
  logType: LOGTYPES;        // Log type
  appName: string;          // Application name
  modName: string;          // Module name
  fnName: string;           // Function name
  entryTS: Date;            // Log entry timestamp in UTC
  friendlyMsg: string;      // Log friendly/brief message
  detailMsg?: string;       // Log detail message (ex: StackTrace from Error)
  task?: string;            // Step/task being executed
  durationIsMS?: number;    // Duration taken in millisecond
}
export interface LogEntryWithDuration extends LogEntry {
  endTS: Date;             // Log entry end timestamp in UTC
  durationIsMS?: number;    // Duration taken in millisecond
}

Loggers

Main logger

Logger that takes all parameters

Module logger

High-order logger on top of main logger to pin the module name

Function logger

High-order logger on top of module logger to pin the function name

Log Output Override

This logger helper module does not actually output the log entries. It expects a logger output to be assigned via setLoggerOutput() function available from the main logger interface.

export type LoggerOutput = (entry: Readonly<LogEntry> | Readonly<LogEntryWithDuration>) => void;

Example

https://github.com/simplyappdevs/logging-helper-example

Reminder for ESM Application

npm exec command option

You will need to run your application with --es-module-specifier-resolution=node option.

Ex: "exec": "node --es-module-specifier-resolution=node ./dist/index.js" for your NPM script npm run exec.

Configure package.json

Set type to module "type": "module"

{
  "name": "my-awesome-app",
  "version": "1.0.0",
  "description": "My Awesome App",
  "main": "index.js",
  "type": "module",
  "scripts": {
  }
}

Configure tsconfig.json

Set module to one of ECMA script "module": "esnext" in compilerOptions section

{
  "compilerOptions": {
    "module": "esnext",
  }
}

Set module resolution to node "moduleResolution": "node" in compilerOptions section

{
  "compilerOptions": {
    "moduleResolution": "node",
  }
}

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