Data mapper chain
Simple data mapper library meant to be run in browser to ease data transformation for IoT devices in JS.
Example: Simple in browser
<body>
...
<script src="https://cdn.jsdelivr.net/npm/@lab5e/data-mapper-chain"></script>
<script>
var myMapper = dmc
.create()
.chunk({ start: 2, size: 2 })
.hexToInt();
console.log(myMapper.mapData("babe")); // Prints 190
</script>
</body>Codepen example
Play around with this Codepen pen for a real life example usage of the data-mapper-chain.
Example: In ts
You must first install the dependency
npm i @lab5e/data-mapper-chainUsing shorthand
import { DataMapperChain } from "@lab5e/data-mapper-chain";
// Create a chain and add mappers
const dataMapperChain = new DataMapperChain()
.chunk({
start: 50,
size: 4,
})
.hexToInt();
// Raw data from device
const deviceData: string = `47eee3803e3a8c713f8daf7242fc6666423c28c04111d84000024b00a3030c261b010b91d3`;
// Run mapper
dataMapperChain.mapData(deviceData); // prints 587Instanciating mappers directly
import { DataMapperChain, Mappers } from "@lab5e/data-mapper-chain";
/**
* We know that on byte 25 there is 2 bytes of data which is a hex encoded uint16
* We solve this by doing the following:
*/
/**
* Create a Chunk mapper
*/
const chunk = Mappers.chunk({
start: 50,
size: 4,
});
/**
* Create a HexToInt mapper
*/
const hexToInt = Mappers.hexToInt();
// Create a DataMapperChain
const dataMapperChain = new DataMapperChain();
// Add mappers
dataMapperChain.addMapper(chunk);
dataMapperChain.addMapper(hexToInt);
// Raw data from device
const deviceData: string = `47eee3803e3a8c713f8daf7242fc6666423c28c04111d84000024b00a3030c261b010b91d3`;
// Run mapper
dataMapperChain.mapData(deviceData); // prints 587Available mappers
All mappers have fully optional configurations, meaning if no configuration is provided it will fallback to sane defaults. It also supports partly providing parameters if you want to just override one option of the mapper.
Base64
Supports encoding and decoding of base64 input.
Chunk
Take a chunk of the input and return it.
FromJSON
Traverse a JSON struct and return value.
HexToFloat
Take a hex input and convert it to a float.
HexToInt
Take a hex input and convert it to an int.
Offset
Take an input and offset it by a positive or negative value.
History
What
The main workhorse is the DataMapperChain which serves a couple of purposes. It contains the different mappers you want to use in your "chain" of mappers and has functions to apply all mappers on a data set. It also allows for serializing configuration of both the chain and the added mappers. This serialized version can again be loaded directly into a new DataMapperChain which is now fully configured with the saved params.
Why
I found myself fiddling with a lot of IoT data recently and a need to graph it easily. The libs which which I found either relied heavily on eval or didn't have any typings. I put together this lib which is modular and pluggable and hopefully solves someones problem alongside mine.
Pluggable
While the lib provide a decent amount of mappers as a starting point, I know I don't cover every use case out there.
Tiny
The library relies mostly on native functions meaning it shouldn't get too big. More complex mappers should be application specific and be a part of the application which imports the library.
Development
We use TSDX for pretty much everything, and most npm scripts just proxy to tsdx.
Run single build
Use npm run build.
Run tests
To run tests, use npm test.
Configuration
Code quality is set up with prettier, husky, and lint-staged.
Jest
Jest tests are set up to run with npm test.
Watch mode
To run in watch mode run npm run test:watch
Coverage
To see coverage run npm run test:coverage
Bundle Analysis
size-limit is set up to calculate the real cost of your library with npm run size and visualize the bundle with npm run analyze.
Rollup
We us TSDX which uses Rollup as a bundler and generates multiple rollup configs for various module formats and build settings. See Optimizations for details.
We create UMD, CommonJS, and JavaScript Modules in our build. The appropriate paths are configured in package.json and dist/index.js
TypeScript
We use TypeScript for everything, giving us types for all the published packages.
Continuous Integration
GitHub Actions
-
mainwhich installs deps w/ cache, lints, tests, and builds on all pushes against a Node and OS matrix -
sizewhich comments cost comparison of your library on every pull request usingsize-limit
Publishing to NPM
We use np. To publish a new version, write npx np and follow the interactive tutorial.