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