Add new JavaScript exercises

One of the easiest ways to add new exercises to the JavaScript track is to translate them from other language tracks on Exercism. This page lists all of the problem specifications in the common pool of exercises which have not yet been implemented in JavaScript.

The icon links to the language-independent description of the problem.

The icon links to the canonical test data.

We also link to all the implementations of each exercise in other languages, which you can use for inspiration.

Once you've picked an exercise, follow the instructions in this guide and submit your pull request to the JavaScript track repository on GitHub.




Bank Account

Simulate a bank account supporting opening/closing, withdraws, and deposits of money. Watch out for concurrent transactions!


Implement a basic reactive system.

Complex Numbers

Implement complex numbers.


Output the nursery rhyme 'This is the House that Jack Built'.

Spiral Matrix

Given the size, return a square matrix of numbers in spiral order.


Make a chain of dominoes.


Pick the best hand(s) from a list of poker hands.

Rail Fence Cipher

Implement encoding and decoding for the rail fence cipher.


Tally the results of a small football competition.

Book Store

To try and encourage more sales of different books from a popular 5 book series, a bookshop has decided to offer discounts of multiple-book purchases.

Parallel Letter Frequency

Count the frequency of letters in texts using parallel computation.


Refactor a Markdown parser


Reparent a graph on a selected node

Scale Generator

Generate musical scales, given a starting note and a set of intervals.

Word Search

Create a program to solve a word search puzzle.

Error Handling

Implement various kinds of error handling and resource management


Search a file for lines matching a regular expression pattern. Return the line number and contents of each matching line.

Zebra Puzzle

Solve the zebra puzzle.

Go Counting

Count the scored points on a Go board.

Dot Dsl

Write a Domain Specific Language similar to the Graphviz dot language

Sgf Parsing

Parsing a Smart Game Format string.

Tree Building

Refactor a tree building algorithm.


Implement the logic of the hangman game using functional reactive programming.


Refactor a ledger printer.

Lens Person

Use lenses to update nested records (specific to languages with immutable data).


Report network IO statistics


Score a single throw of dice in the game Yacht