log-chainable

A utility for organizing javascript log statements into namespaces. Why? Because reading pages of random logs sucks, and you're too lazy/smart to annotate each statement.

Installation

npm install log-chainable

Basic Usage

The most basic usage:

const log = require('log-chainable');
 
log('hi mom'); // [info] hi mom
log.warn('bye mom'); // [warn] hi mom

Using namespaces:

const log = require('log-chainable');
 
const logFamily = log.namespace('greetings').namespace('family');
 
logFamily('hi mom'); // [info] (greetings.family) hi mom

Namespaces are smart:

// greeter.js
 
const log = require('log-chainable');
 
const logGreeter = log.namespace('myApp', 'utils', module); 
logGreeter('greetings'); // [info] (myApp.utils.greeter) greetings

Be concise:

// greeter.js
 
const log = require('log-chainable').namespace('myApp', 'utils', module);
 
class MyClass {
    constructor () {
        this.log = log.namespace(this);
    }
 
    doThatThing () {
        this.log('done doing that thing');
    }
}
 
const myInstance = new MyClass();
myInstance.doThatThing() // [info] (myApp.utils.greeter.MyClass) done doing that thing

Handlers

Each namespace can have it's own handler:

const log = require('log-chainable');
 
log.namespace('myApp', 'mySpecialModule')
    .handler(function myHandler (level, nameStack, args) {
        process.stdout.write(`myHandler: ${ level } ${ nameStack.join('/') } ${ args.join(', ') }\n`);
    });
 
log.namespace('myApp')('one', 'two'); // [info] (myApp) hi mom
log.namespace('myApp', 'mySpecialModule')('one', 'two'); // myHandler: info myApp/mySpecialModule one, two

Handlers cascade to child namespaces:

const log = require('log-chainable');
 
log.namespace('myApp', 'mySpecialModule')
    .handler(function myHandler (level, nameStack, args) {
        process.stdout.write(`myHandler: ${ level } ${ nameStack.join('/') } ${ args.join(', ') }\n`);
    });
 
log.namespace('myApp')('one', 'two'); // [info] (myApp) hi mom
log.namespace('myApp', 'mySpecialModule')('one', 'two'); // myHandler: info myApp/mySpecialModule one, two
log.namespace('myApp', 'mySpecialModule', 'mySpecialChildModule')('three', 'four'); // myHandler: info myApp/mySpecialModule/mySpecialChildModule three, four

log-chainable comes with some handlers included:

const log = require('log-chainable');
const handlers = require('log-chainable/handlers');
 
const myAppLogger = log.namespace('myApp').handler(handlers.default);
 
myAppLogger
    .namespace('colorfulModule')
    .handler(handlers.minimalConsoleColorized);
 
myAppLogger
    .namespace('dullModule')
    .handler(handlers.minimalConsole);

The Default Handler

The default handler is a minimalist call to console.log with some extra colorization.

The default handler will hide .debug() calls unless the DEBUG environment variable is set.

const log = require('log-chainable');
const handlers = require('log-chainable/handlers');
 
// this equivalent is already set for you
log.handler(handlers.default)
 
process.env['DEBUG'] = undefined;
log.debug('beep beep beep'); // <nothing happens>
 
process.env['DEBUG'] = 'true';
log.debug('beep beep beep'); // [debug] beep beep beep

List of Available Handlers

• handlers.minimalConsoleColorized aka the default handler
• handlers.minimalConsole same as above with no color

Feel free to contribute more. Speaking of ...

Contributing

Just please run the tests and linter.

npm run check