Creating powerful yet simple Markov Chains in JavaScript

js-markov

js-markov is a JavaScript library that allows you to create powerful Markov Chains.

Motivation behind js-markov

js-markov was designed to make using Markov Chains much easier, thus allowing you to create powerful text generation programs.

Live demo

A live demo of js-markov can be seen on JavaScript repo name generator .

Code Example

The following example shows the basic usage js-markov.

// Create a new Markov Chain
var markov = new Markov();

// Add some states
markov.addState([
  'Today is sunny',
  'Today is rainy',
  'The weather is sunny',
  'The weather for tomorrow might be rainy'
]);

// Train the Markov Chain
markov.train();

// Generate an output
markov.generate();

Installation

There are two ways to get a copy of js-markov:

• For developing your project in the browser, all you need to do is to include the CDN link:

  <script src="https://unpkg.com/js-markov/dist/markov.js"></script>

• For Node.js users, all you have to do is install it with NPM:

  npm install --save js-markov

  Then, you'll be able to include in your code:

  const Markov = require('js-markov');

Usage

Before using js-markov, you'll need to create a new Markov object.

var markov = new Markov();

After that, we can have some fun!

The next part that we need to do is to add states. A state is a form of an object. In js-markov, a state is a word.

There are two ways to add states:

• Use an array

  markov.addState([
    'Today is sunny',
    'Today is rainy',
    'The weather is sunny',
    'The weather for tomorrow might be rainy'
  ]);

• Add a single state

  markov.addState('The weather for tomorrow might be sunny');

Awesome :sunglasses:

Now we can train our Markov Chain. The method train receives an optional "order" parameter. This order defaults to 3.

The order is only used for dividing the states into ngrams.

markov.train();

// Or
markov.train(3);

It is time :smiley:

Now we are ready to generate some text!

All we have to do is to use the generate method. This method receives an option parameter which will be used to limit the length of the text. By default, it is set to 15.

var text = markov.generate();

// Or 
var longText = markov.generate(50);

Advanced usage

These are some advanced methods that js-markov offers.

Cleaning things up

• clearChain()

  markov.clearChain();

  This method will reset the whole Markov Chain .

  Once the method is run, you will have a Markov Chain that looks new.

• clearState()

  markov.clearState();

  This method will reset two properties:

  markov.states = [];
  markov.start = [];

  This is good if you want to refresh all of your states.

• clearPossibilities()

  markov.clearPossibilities();

  This method will reset the possibilities property to an empty object.

  This is method called in the train() method.

Getting values

• getStates()

  var states = markov.getStates();

  Returns an array of all the states in the Markov Chain.

• getPossibilities()

  This function can do two things:

  • If it is not supplied with an argument, It will the whole object:

    var possibilities = markov.getPossibilities();

  • If there is a valid parameter, then it will return an array of all the possibilities:

  var possibilities = markov.getPossibilities('Hey');

• getOrder()

  var order = markov.getOrder();

  Returns the order of the Markov Chain.

Miscellaneous methods

• setOrder()

  markov.setOrder(4);

  Sets the order of the Markov Chain. If no parameter is passed, setOrder will use the value of 3.

• random()

  markov.random(obj, type)

  This is used in the generate method to generate the new text.

  random() receives two parameters:

  • obj - The object or array that gets passed

  • type - The type of value been passed to obj ( 'object' or 'array' )

  Returns a random value from an array or a random key from an object.

Contributing

If you are interested in contributing, please have a look at the contributing guidelines .

License

js-markov is licensed under the MIT License. Please have a look at the LICENSE file for more information.