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Contributing guidelines

Before contributing

Welcome to TheAlgorithms/JavaScript! Before sending your pull requests, make sure that you read the whole guidelines. If you have any doubts about the contributing guide, please feel free to state them clearly in an issue or by joining our Discord community.



We are very happy that you consider implementing algorithms and data structures for others! This repository is referenced and used by learners from around the globe. Being one of our contributors, you agree and confirm that:

  • You did your work - plagiarism is not allowed.
    • Any plagiarized work will not be merged.
  • Your work will be distributed under the GNU GPLv3.0 once your pull request is merged.
  • Your submitted work must fulfill our styles and standards.

New implementations are welcome! For example, new solutions to a problem, different representations of a graph data structure, or algorithm designs with different complexity.

Improving comments and writing proper tests are also highly welcome.


We appreciate any contribution, from fixing grammar mistakes to implementing complex algorithms. Please read this section if you are contributing to your work.

If you submit a pull request that resolves an open issue, please help us to keep our issue list small by adding fixes: #{$ISSUE_NO} to your commit message. GitHub will use this tag to auto-close the issue if your PR is merged.

What is an Algorithm?

An Algorithm is one or more functions (or classes) that:

  • take one or more inputs.
  • perform some internal calculations or data manipulations.
  • return one or more outputs.
  • have minimal side effects.

Algorithms should be packaged in a way that would make it easy for readers to put them into larger programs.

Algorithms should:

  • have intuitive class and function names that make their purpose clear to readers.
  • use JavaScript naming conventions and intuitive variable names to ease comprehension.
  • be flexible to take different input values.
  • raise JavaScript exceptions (RangeError, etc.) on erroneous input values.

Algorithms in this repo should not be how-to examples for existing JavaScript packages. Instead, they should perform internal calculations or manipulations to convert input values into different output values. Those calculations or manipulations can use data types, classes, or functions of existing JavaScript packages but each algorithm in this repo should add a unique value.

Commit guidelines

  • Follow Conventional Commits guidelines at all times.
  • Use one of the following prefixes (there might be other miscellaneous prefixes, though).
    • fix: A bug fix in an algorithm, workflow, configuration/settings, etc..
    • feat: A new feature, such as new algorithms, new workflows, etc..
    • docs: Documentation changes or fixes, like improving the contributing guidelines, fixing a typo, etc..
    • test: Correct existing tests or add new ones.
    • chore: Miscellaneous changes that do not match any of the above.

Examples of best commit messages.

fix: fixed error in XYZ algorithm
feat: re-work the CI workflow
docs: improve the contributing guidelines
test: add self-tests for XYZ algorithm
chore: update readme badges

File Naming Convention

  • Filenames should use the UpperCamelCase (PascalCase) style.
  • There should be no spaces in filenames.
  • Example: UserProfile.js is allowed but userprofile.js,Userprofile.js,user-Profile.js,userProfile.js are not.

Module System

We use the ES Module system, which brings an official, standardized module system to JavaScript.

It roughly means you will need to use export and import statements instead of module.exports and require().


Be confident that your code works. When was the last time you committed a code change, your build failed, and half of your app stopped working? Mine was last week. Writing tests for our Algorithms will help us ensure the implementations are airtight even after multiple fixes and code changes.

We use Jest to run unit tests on our algorithms. It provides a very readable and expressive way to structure your test code.

It is advised that the algorithm file (module) does not contain any "live" code but rather just exports the function(s) needed to execute the algorithm. Your test code can import those function(s), call them with the appropriate parameters and inspect the outcome. Example: RatInAMaze.test.js.

Please refrain from using console in your implementation AND test code.

First, you should install all dependencies using:

npm install

You can (and should!) run all tests locally before committing your changes:

npm test

If you want to save some time and just run a specific test:

# This will run any test file where the filename contains "koch" (no need to specify folder path)
npm test -- koch

You can also start Jest in "watch" mode:

npm test -- --watchAll

We also prepared a helper script that runs tests only for changed files:

npm run test-changed

This will run all tests and watch source and test files for changes. When a change is made, the tests will run again.

Coding Style

To maximize the readability and correctness of our code, we require that new submissions follow the JavaScript Standard Style.

Before committing, please run:

npm run style

In order to apply the coding style (where it can be done automatically). If an error is shown, please figure out what's wrong, fix it and run standard again.

A few (but not all) of the things to keep in mind:

  • Use camelCase with the leading character as lowercase for identifier names (variables and functions).
  • Names start with a letter.
  • Follow code indentation: Always use 2 spaces for code-block indentation.
function sumOfArray(arrayOfNumbers) {
  let sum = 0

  for (let i = 0; i < arrayOfNumbers.length; i++) {
    sum += arrayOfNumbers[i]

  return sum
  • Avoid using global variables and avoid ==.
  • Please use let over var.
  • Please refrain from using console.log or any other console methods.
  • Absolutely don't use alert.
  • We strongly recommend the use of ECMAScript 6.
  • Avoid importing external libraries for basic algorithms. Only use those libraries for complicated algorithms.
  • Most importantly:
    • Be consistent in the use of these guidelines when submitting.
    • Happy coding!

Writer @itsvinayak and contributors, May 2020.