@node-cli/logger

Node CLI Logger

Logger is a dead-simple console logger for nodejs command-line applications.

Installation

> cd your-project
> npm install --save-dev @node-cli/logger

2 classes are available:

• Logger which is a facade for console and with added methods, such as printBox()
• Spinner is an "elegant terminal spinner", relying behind the scenes on the excellent ora

Usage

import { Logger } from "@node-cli/logger";
const log = new Logger();

log.info("this is an informational log");
log.warn("this is a warning log");
log.error("this is an error log");

import { Spinner } from "@node-cli/logger";
const spinner = new Spinner("Updating package.json...");

// assuming a long running process here...
spinner.text = "Git stage and commit, please wait...";
// assuming a long running process here...
spinner.text = "Almost there...";
// assuming a long running process here... returning some result
if (result === "success") {
	spinner.stop("Process completed successfully!");
} else {
	spinner.stop("Process failed miserably...", Spinner.ERROR);
}

API

Spinner methods

Method	Arguments	Description
constructor	options	Initialize a Spinner instance with ora options
start	text	Starts the spinner on the terminal and append a string to it
stop	text, status	Stop the spinner, change it to a green, red, yellow or blue marker, and persist the current text, or text if provided. The argument status can be one of Spinner.SUCCESS, Spinner.ERROR, Spinner.WARNING or Spinner.INFO

Setter	Description
text	Set the text of the spinner. If the spinner is stopped, the text will be persisted.

Logger methods

Logger relies on console behind the scenes, and therefore supports the same string substitution capabilities and uses the following methods:

Method	Description	Output color
debug	Outputs a message to the console with the log level debug	grey
log	For general output of logging information.	white
info	Informative logging of information.	blue
warn	Outputs a message to the console with the log level debug	yellow
error	Outputs an error message.	red
printBox	Output message(s) in a box	custom
printErrorsAndExit	Output error message(s) and exit	red

Options

Disabling logging

You can disable logging with silent:

import { Logger } from "@node-cli/logger";
const log = new Logger();

log.info("this will be logged");
// disabling logs in production for example
log.silent = process.env.NODE_ENV === "production";
log.info("but this will not");
log.silent = false;
log.info("this will be logged again!");

This option can also be passed to the constructor:

import { Logger } from "@node-cli/logger";
const log = new Logger({ silent: true });

log.info("this will not be logged");
log.silent = false;
log.info("this will be logged again!");

Disabling colors

You can disable colors with boring:

import { Logger } from "@node-cli/logger";
const log = new Logger();

log.info("this will be logged in the default [info] color");
// disabling colors in test mode for example
log.boring = process.env.NODE_ENV === "test";
log.info("but this will not have any colors :/");
log.boring = false;
log.info("colors are back!");

This option can also be passed to the constructor:

import { Logger } from "@node-cli/logger";
const log = new Logger({ boring: true });

log.info("this will not be logged in color");
log.boring = false;
log.info("this will be logged again!");

Adding a prefix

You can add a prefix to the logs with prefix:

import { Logger } from "@node-cli/logger";
const log = new Logger();

log.info("this will be logged with no prefix");
log.prefix = "[INFO]";
log.info("this will have a prefix!");

The output of that last line would be:

> [INFO] this will have a prefix!

This option can also be passed to the constructor:

import { Logger } from "@node-cli/logger";
const log = new Logger({ prefix: "Log:" });

log.info("this will be logged with a prefix");
log.prefix = false;
log.info("this will be NOT be logged with a prefix");

Adding a local timestamp

You can add a timestamp to the logs with timestamp:

import { Logger } from "@node-cli/logger";
const log = new Logger();

log.info("this will be logged with no timestamp");
log.timestamp = true;
log.info("this will have a timestamp!");

The output of that last line would look like:

> [ Tue Feb 02 2021 8:32:58 PM ] this will have a timestamp!

This option can also be passed to the constructor:

import { Logger } from "@node-cli/logger";
const log = new Logger({ timestamp: true });

log.info("this will be logged with a timestamp");
log.timestamp = false;
log.info("this will be NOT be logged with a timestamp");

Log one or more messages in a box

The printBox method is a wrapper around the excellent Boxen, with sensible defaults.

import { Logger } from "@node-cli/logger";
const log = new Logger();

log.printBox(["Message One!", "Message Two!"]);

┌──────────────────┐
│                  │
│   Message One!   │
│   Message Two!   │
│                  │
└──────────────────┘

printBox accepts the following options as a second argument:

• printLineAfter (default to true)
• printLineBefore (default to true)
• As well as all the options available with Boxen

Here is a custom example with:

• a red border color
• no extra line after the box
• no padding (no space between the border and the text)
• text is justified to the right
• there is a title injected at the top of the box

import { Logger } from "@node-cli/logger";
const log = new Logger();

log.printBox(["Message One!", "Message Two!"], {
	borderColor: "red",
	newLineAfter: false,
	padding: 0,
	textAlignment: "right",
	title: "Hello World Box Title",
});

Log multiple errors and optionally exit the main program

The following will print 2 error messages and exit with error code 666. If the second parameter (a number) is not provided, the process does not exit.

import { Logger } from "@node-cli/logger";
const log = new Logger();

log.printErrorsAndExit(["Error One!", "Error Two!"], 666);

License

MIT © Arno Versini