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.

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:

API

The module exports the following API:

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<string>;
    circo(dotSource: string, outputFormat?: Format): Promise<string>;
    dot(dotSource: string, outputFormat?: Format): Promise<string>;
    fdp(dotSource: string, outputFormat?: Format): Promise<string>;
    neato(dotSource: string, outputFormat?: Format): Promise<string>;
    osage(dotSource: string, outputFormat?: Format): Promise<string>;
    patchwork(dotSource: string, outputFormat?: Format): Promise<string>;
    twopi(dotSource: string, outputFormat?: Format): Promise<string>;
};

graphviz.layout(dotSource[, outputFormat][, layoutengine])

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

graphviz.circo(dotSource[, outputFormat])

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

graphviz.dot(dotSource[, outputFormat])

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

graphviz.fdp(dotSource[, outputFormat])

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

graphviz.neato(dotSource[, outputFormat])

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

graphviz.osage(dotSource[, outputFormat])

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

graphviz.patchwork(dotSource[, outputFormat])

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

graphviz.twopi(dotSource[, outputFormat])

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