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🐛 How to report a bug

Please note

The high-level structure of Turf is undergoing discussion at #1428. Currently (June 2018), there is a partial conversion to Typescript, and the contribution documentation does not completely reflect the current status.

How To Contribute

  • Most work happens in sub modules. These are found in the packages directory prefixed with "turf-".
  • If you would like to propose a new feature, open an issue in Turfjs/turf.
  • Always include tests. We use tape.
  • Turf modules are small, containing a single exported function.
  • GeoJSON is the lingua franca of Turf. It should be used as the data structure for anything that can be represented as geography.
  • Avoid large dependencies at all costs.
  • Turf is used in a wide range of places. Make sure that your code can run in the browser (ie: don't make calls to external services, don't hit the filesystem, etc.).
  • The files in packages/turf-<module> are automatically generated from the JSDocs of the index.js. Please modify the JSDocs instead of modifying the files directly. Then update/create the executing ./scripts/generate-readmes or runing npm run docs from the root TurfJS directory.
  • Finally run npm test from the project root folder to run all the tests required for deploying the project.

Code Style

To ensure code style, at the turf root level run

$ npm run lint

Structure of a turf module

│   index.js
│   index.d.ts
│   bench.js
│   test.js
│   types.ts
│   package.json
    │   points.geojson

To get started with a new module navigate to the root directory and run

$ node ./scripts/create-new-module <MODULE NAME>

it will create a new folder inside packages with a simple boilerplate for your module.

  • index.js - This file contains, in order, the various modules you need to import, the JSDocs documentation, and, finally, the single exported function that the module provides. For more on the types supported in the documentation, see…
  • index.d.ts - This is a TypeScript file that describes your function’s signature. For more on the types supported in TypeScript, see…
  • bench.js - This file uses Benchmark to time your function.
  • test.js - This file includes your tape tests. We prefer dynamic testing built from GeoJSON files placed in ./test/in that are subsequently written to ./test/out if your REGEN environment variable is set to true. If REGEN is set to a different value, then running npm t will compare the output of the tests to the files already present in ./test/out.
  • types.ts - A file that lists the custom TypeScript types used in index.d.ts.
  • package.json - The node metadata container file. Modules imported in index.js should be listed here under dependencies, and modules used in test.js and/or bench.js should be listed under devDependencies. npm install looks to this file to install dependencies in ./node_modules.
  • - This README is generated automatically by running npm run docs from the project root level. DO NOT edit this file.
  • LICENCE - Like the README, this file should not be edited.
  • test/ - This directory holds the GeoJSON files that provide data for dynamic tests (in ./test/in) and the results of the tests (in ./test/out). The files in ./test/out should not be edited by hand. They should be generated dynamically by setting the environment variable REGEN to true, and then the tests should be checked against these files by setting REGEN to some other value. The resulting out-files can be drag-dropped into to see, visually, if the module is behaving appropriately.


Install lerna:

$ npm install -g lerna@2.0.0-beta.34

Publish a test release:

$ lerna publish --canary


To update TurfJS's Documentation ( use the following npm run docs:

  • inside a module: will only generate the docs of that module.
  • main folder: will generate docs for all modules.

Documentation - Examples

Only builds docs for @turf/center

$ cd ./turf/packages/turf-center
$ npm run docs

> @turf/center@5.0.4 docs /Users/mac/Github/turf/packages/turf-center
> node ../../scripts/generate-readmes

Building Docs: @turf/center

Builds docs for all modules

$ cd ./turf
$ npm run docs
> @5.0.0 docs /Users/mac/Github/turf
> node ./scripts/generate-readmes

Building Docs: @turf/along
Building Docs: @turf/area
Building Docs: @turf/bbox-clip
Building Docs: @turf/bbox-polygon
Building Docs: @turf/bbox
Building Docs: @turf/bearing
Building Docs: @turf/bezier-spline
Building Docs: @turf/boolean-clockwise

Other Dependencies

  • Turf uses Yarn and lerna during the testing, packaging and publishing process.
    • Lerna will be automatically installed when you run npm install in the root directory.
    • Yarn will need to be installed on your computer, installers are available via the yarn website.

Financial contributions

We also welcome financial contributions in full transparency on our open collective. Anyone can file an expense. If the expense makes sense for the development of the community, it will be "merged" in the ledger of our open collective by the core contributors and the person who filed the expense will be reimbursed.



Thank you to all the people who have already contributed to turf!


Thank you to all our backers! [Become a backer]


Thank you to all our sponsors! (please ask your company to also support this open source project by becoming a sponsor)

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