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Transducer based UI updater for @thi.ng/hdom. This is a support package for @thi.ng/transducers.

This package provides a single updateDOM function, a side-effecting & stateful transducer which receives @thi.ng/hdom component trees, diffs each against the previous value and applies any required changes to the browser DOM, starting at given root element. By default, incoming values are first normalized using @thi.ng/hdom's normalizeTree() function. See hdom's start() function for more details.

If the hydrate option is given, the first received tree is only used to inject event listeners and initialize components with lifecycle init() methods and expects an otherwise identical pre-existing DOM. All succeeding trees are diffed then as usual.

This transducer is primarily intended for @thi.ng/rstream-based dataflow graphs, where it can be used as final leaf subscription / stream transformer to reflect UI changes back to the user, without using the usual RAF update loop used by @thi.ng/hdom by default. In this setup, DOM updates will only be performed if the stream this transducer is attached to receives new values (i.e. hdom component trees).

Please also see the following hdom references for further details:

• start()
• HDOMOpts

STABLE - used in production

Search or submit any issues for this package

• @thi.ng/hdom - Lightweight vanilla ES6 UI component trees with customizable branch-local behaviors
• @thi.ng/interceptors - Interceptor based event bus, side effect & immutable state handling
• @thi.ng/rstream - Reactive streams & subscription primitives for constructing dataflow graphs / pipelines

yarn add @thi.ng/transducers-hdom

ES module import:

<script type="module" src="https://cdn.skypack.dev/@thi.ng/transducers-hdom"></script>

Skypack documentation

For Node.js REPL:

# with flag only for < v16
node --experimental-repl-await

> const transducersHdom = await import("@thi.ng/transducers-hdom");

Package sizes (gzipped, pre-treeshake): ESM: 297 bytes

• @thi.ng/hdom
• @thi.ng/hiccup
• @thi.ng/transducers

Several demos in this repo's /examples directory are using this package.

A selection:

Screenshot	Description	Live demo	Source
	Interactive image processing (adaptive threshold)	Demo	Source
	Figlet-style bitmap font creation with transducers	Demo	Source
	Canvas based dial widget	Demo	Source
	Basic crypto-currency candle chart with multiple moving averages plots	Demo	Source
	Interactive inverse FFT toy synth	Demo	Source
	Doodle w/ K-nearest neighbor search result visualization	Demo	Source
	Mouse gesture / stroke analysis, simplification, corner detection	Demo	Source
	Interactive pattern drawing demo using transducers	Demo	Source
	Various hdom-canvas shape drawing examples & SVG conversion / export	Demo	Source
	Isolated, component-local DOM updates	Demo	Source
	Canvas based Immediate Mode GUI components	Demo	Source
	Worker based, interactive Mandelbrot visualization	Demo	Source
	Minimal Markdown to Hiccup to HTML parser / transformer	Demo	Source
	Basic rstream-gestures multi-touch demo	Demo	Source
	Polygon to cubic curve conversion & visualization	Demo	Source
	Animated Voronoi diagram, cubic splines & SVG download	Demo	Source
	Minimal demo of using rstream constructs to form an interceptor-style event loop	Demo	Source
	rstream based UI updates & state handling	Demo	Source
	rstream based spreadsheet w/ S-expression formula DSL	Demo	Source
	hdom based slide deck viewer & slides from my ClojureX 2018 keynote	Demo	Source
	Transducer & rstream based hdom UI updates	Demo	Source

Generated API docs

Code for the above linked transducers-hdom example...

import * as rs from "@thi.ng/rstream";
import * as tx from "@thi.ng/transducers";
import { updateDOM } from "@thi.ng/transducers-hdom";

// root component function
const app = ({ ticks, clicks }) =>
    ["div",
        `${ticks} ticks and `,
        ["a",
            { href: "#", onclick: () => clickStream.next(0) },
            `${clicks} clicks`]
    ];

// click stream (click counter)
const clickStream = new rs.Stream().transform(tx.scan(tx.count(-1)));

// stream combinator
rs.sync({
    src: {
        ticks: rs.fromInterval(1000),
        clicks: clickStream,
    },
    reset: false,
}).transform(
    // transform into hdom component
    tx.map(app),
    // apply as DOM
    updateDOM({ root: document.body })
);

// kick off
clickStream.next(0);

Karsten Schmidt

If this project contributes to an academic publication, please cite it as:

@misc{thing-transducers-hdom,
  title = "@thi.ng/transducers-hdom",
  author = "Karsten Schmidt",
  note = "https://thi.ng/transducers-hdom",
  year = 2018
}

© 2018 - 2021 Karsten Schmidt // Apache Software License 2.0