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Left, Right, Up, Down. A spatial navigation library for devices with input via directional controls.


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LRUD Build Status

A spatial navigation library for devices with input via directional controls

🔩 Maintenance Mode 🔩

LRUD is now in maintenance mode; existing bugs will be fixed, but new features will not be added. A new library called LRUD Spatial is now available to the Open Source community.

Upgrading from V2

v3 is a major rewrite, covering many new features. However, it unfortunately breaks some backwards compatibility.

We are currently in the process of writing more detailed docs for an upgrade process. However, the main things to note at the minute at;

  • changes in events, which ones are emitted and what they are emitted with
  • removal of grid in favour of isIndexAligned behaviour

Getting Started

git clone lrud
cd lrud
npm install

Lrud is written in Typescript and makes use of mitt.


npm install lrud
const { Lrud } = require('Lrud')

// create an instance, register some nodes and assign a default focus
var navigation = new Lrud()
  .registerNode('root', { orientation: 'vertical' })
  .registerNode('item-a', { parent: 'root', isFocusable: true })
  .registerNode('item-b', { parent: 'root', isFocusable: true })

// handle a key event
document.addEventListener('keypress', (event) => {

// Lrud will output an event when it handles a move
navigation.on('move', (moveEvent) => {

See usage docs for details full API details.

For more "full" examples, covering common use cases, check the recipes

Running the tests

All code is written in Typescript, so we make use of a tsconfig.json and jest.config.js to ensure tests run correctly.

Test files are split up fairly arbitrarily, aiming to have larger sets of tests broken into their own file.

npm test

To run a specific test file, use npx jest from the project root.

npx jest src/lrud.test.js

You can also run all the tests with verbose output. This is useful for listing out test scenarios to ensure that behaviour is covered.

npm run test:verbose

You can also run all the tests with coverage output

npm run test:coverage

Several of the tests have associated diagrams, in order to better explain what is being tested. These can be found in ./docs/test-diagrams.

We also have a specific test file (src/build.test.js) in order to ensure that we haven't broken the Typescript/rollup.js build.


npm version <patch:minor:major>
npm publish

Built with




LRUD is part of the BBC TAL libraries, and available to everyone under the terms of the Apache 2 open source licence (Apache-2.0). Take a look at the LICENSE file in the code.

Copyright (c) 2018 BBC