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logan

Logan

Logan is a mini template system for the console and colors.

It allows to cleanly separate content from style and create beautiful logging functions.

Example

Let's say you want to write a logging function that says hello.

// Without Logan 
function hello(arg) {
  console.log('Hello'.bold.green + ' : ' + arg.cyan);
}
 
// With Logan 
var hello = logan.create('Hello : %', 'bold.green . cyan')
 
hello('world');

Usage

var logan = require('logan');

set

This is the most useful method of logan. It lets you define all your templates in one place.

logan.set({
  info: ['info : %', 'yellow'],
  warn: ['warn : %', 'orange'],
  omg : ['omg  : %', 'rainbow']
});
 
logan.info('some info');

Notice how easy it is to see what all your logging functions will output.

Also, with set your module users can easily theme logs:

// Overriding omg to be... more OMG!!! 
logan.set({
  omg: ['OMG : % !!!', 'red . . red']
});

create

Returns a logging function.

var info = logan.create('info : %', 'yellow');
info('some text');

compile

Returns a function which returns a string when called.

var info = logan.compile('info : %', 'yellow');
console.log(info('some text'));

Syntax

  • % is used for string replacement.
  • {} lets you define blocks.
  • . means default style.
  • styles can be chained (example: bold.underline.red).

{} usage:

// for example, instead of writing this: 
var green = logan.create('some long green string', 'green green green green');
 
// using {} you can write 
var green = logan.create('{some long green string}', 'green');

Configuration

If you want to suppress all output, during tests for example, just set silent to true.

logan.set({'foo', ['foo', 'red']});
logan.silent = true;
logan.foo(); // No output 
logan.silent = false;
logan.foo(): // will output 'foo' 

About the name

Since there's a templating engine called hogan and this one is about logging, it was called logan.

More

If you want to see how Logan can be used in another project, you can have a look at ShoutJS.