@shopify/logger

Opinionated logger for production-scale applications

Usage no npm install needed!

<script type="module">
  import shopifyLogger from 'https://cdn.skypack.dev/@shopify/logger';
</script>

README

@shopify/logger

Build Status Build Status License: MIT npm version

Opinionated logger for production-scale applications.

Installation

$ yarn add @shopify/logger

Usage

Instantiation

A basic logger can be created simply by calling the Logger constructor:

const logger = new Logger();

The Logger constructor also takes an options object. For example:

const logger = new Logger({
  name: 'my-logger',
  formatter: new ConsoleFormatter(),
});

The options object adheres to the following interface:

interface LoggerOptions {
  formatter?: Formatter;
  name?: string;
}

The name of a logger will be used as it's root scope. A formatter may use this to provide context when outputting a log entry. For example, the ConsoleFormatter will preface each log with its scope, such as:

[my-logger] ℹ info - some log text

A Formatter is simply an object that implements the Formatter interface:

export interface Formatter {
  format(entry: FormatEntry): any;
}

In addition to writing your own formatter, See Formatters below for a list of provided formatters.

Logging

Given the logger above, we can log information to the console using the built-in info, warn, and error functions. For example:

logger.info('Hello, world!');
logger.warn('Something bad might happen');
logger.error(new Error('Operation not permitted.'));

Formatters

This package provides the following formatters:

  • ConsoleFormatter

ConsoleFormatter

Formats and prints logs via console.log, console.warn, and console.error.

Screenshots

ConsoleFormatter sample error output

ConsoleFormatter sample log output on a dark background

ConsoleFormatter sample log output on a light background