node-graphviz

A JS + WASM module for compiling graphs written in DOT to images, using GraphViz in Node.js.

No annoying native build system or native dependencies that need to be compiled.

Installation

``
npm install node-graphviz --save
`

Usage

See The DOT Language for more information about DOT, and GraphViz Pocket Reference for some examples.

`js
const fs = require('fs');
const { graphviz } = require('node-graphviz');

// Define a graph using DOT notation
const graph =
digraph {
a -> b;
b -> c;
c -> d;
d -> a;
}
;

// Compile the graph to SVG using the circo layout algorithm
graphviz.circo(graph, 'svg').then((svg) => {
// Write the SVG to file
fs.writeFileSync('graph.svg', svg);
});
`

Running the above produces the following SVG:

!SVG Image showing compiled graph

API

The module exports the following API:

`ts
declare type Format = 'svg' | 'dot' | 'json' | 'dot_json' | 'xdot_json';

declare type Engine = 'circo' | 'dot' | 'fdp' | 'neato' | 'osage' | 'patchwork' | 'twopi';

export declare const graphviz = {
layout(dotSource: string, outputFormat?: Format, layoutEngine?: Engine): Promise;
circo(dotSource: string, outputFormat?: Format): Promise;
dot(dotSource: string, outputFormat?: Format): Promise;
fdp(dotSource: string, outputFormat?: Format): Promise;
neato(dotSource: string, outputFormat?: Format): Promise;
osage(dotSource: string, outputFormat?: Format): Promise;
patchwork(dotSource: string, outputFormat?: Format): Promise;
twopi(dotSource: string, outputFormat?: Format): Promise;
};
`

$3

Performs layout for the supplied dotSource.

Where:

- outputFormat is one of the following (see Output Formats for details):
- dot
- dot_json
- json
- svg (default)
- xdot_json
- layoutEngine is one of the following (see Layout documentation for details):
- circo
- dot (default)
- fdp
- neato
- osage
- patchwork
- twopi

$3

Convenience function that performs circo layout, is equivalent to layout(dotSource, outputFormat, 'circo').

$3

Convenience function that performs dot layout, is equivalent to layout(dotSource, outputFormat, 'dot').

$3

Convenience function that performs circo layout, is equivalent to layout(dotSource, outputFormat, 'fdp').

$3

Convenience function that performs neato layout, is equivalent to layout(dotSource, outputFormat, 'neato').

$3

Convenience function that performs osage layout, is equivalent to layout(dotSource, outputFormat, 'osage').

$3

Convenience function that performs patchwork layout, is equivalent to layout(dotSource, outputFormat, 'patchwork').

$3

Convenience function that performs twopi layout, is equivalent to layout(dotSource, outputFormat, 'twopi')`.

Credits

This module is based on hpcc-systems/hpcc-js-wasm, which is designed for use in a browser, not Node.js. The following changes were made to support Node and simplify the module to include only GraphViz:

- Rewrote WASM binary location and fetching to read from the filesystem
- Added the compiled WASM binary to the source
- Reduced the JS code by half to include only GraphViz, removed Expat and other unrelated code
- Removed build system and TypeScript, in favor of a single source file (based on the compiled dist file from hpcc-systems/hpcc-js-wasm)

Licence

MIT