gulp-marked-vega

gulp plugin to replace marked-vega codeblocks with base64 image markdown tags so that any markdown parser can render the Vega or Vega-Lite charts as images.

Currently, only the marked-vega codebase markdown is supported. The image markdown is not supported yet.

API documentation can be found at https://e2fyi.github.io/gulp-marked-vega.

Installation

Yarn

yarn add gulp-marked-vega -D

Npm

npm install gulp-marked-vega -D

Usage

Gulp

Replacing marked-vega codeblocks with image. Export as markdown.

const gulp = require('gulp');
const marked_vega = require('gulp-marked-vega');
 
gulp
  .src('./test/sample.md')
  .pipe(marked_vega()) // replace codeblocks with image
  .pipe(gulp.dest('test/output')); // output as "test/output/sample.md"
 

Replacing marked-vega codeblocks with image. Export as HTML. Auto rename to <original_filename>.html.

const gulp = require('gulp');
const marked_vega = require('gulp-marked-vega');
 
gulp
  .src('./test/sample.md')
  .pipe(marked_vega(true)) // replace codeblocks with image and export as html
  .pipe(gulp.dest('test/output')); // output as "test/output/sample.html"
 

More details on how to use Gulp as part of your build chain can be found at their site.

Cli

There is also a cli to directly embed the Vega and Vega-Lite charts in your markdown file.

usage: mdvg.js [-h] [-v] -f FILE [-o OUTPUT] [--html]

cli to replace marked-vega codeblocks with base64 embedded charts.

Optional arguments:
  -h, --help            Show this help message and exit.
  -v, --version         Show program's version number and exit.
  -f FILE, --file FILE  Input markdown file to process
  -o OUTPUT, --output OUTPUT
                        Output file to write to
  --html                Convert to HTML

Embed chart only.

mdvg -f ./test/sample.md -o ./test/sample_.md

Embed and convert to HTML.

mdvg -f ./test/sample.md -o ./test/sample_.md --html

marked-vega custom Markdown Syntax

marked-vega introduces a few new markdown syntax.

1. Image markdown

Syntax

![vg|vega|vega-lite|vl](https://someurl/spec.json)

Example

![vega](barchart-vg.json)

2. Code markdown

Syntax

```vg|vega|vega-lite|vl
<Vega/Vega-Lite JSON specification>
or
<Vega/Vega-Lite JSON specification in YAML format>
```

Example - JSON specification

```vega-lite
{
  "data": {
    "values": [
      {"a": "A","b": 28}, {"a": "B","b": 55}, {"a": "C","b": 43},
      {"a": "D","b": 91}, {"a": "E","b": 81}, {"a": "F","b": 53},
      {"a": "G","b": 19}, {"a": "H","b": 87}, {"a": "I","b": 52}
    ]
  },
  "mark": "bar",
  "encoding": {
    "x": {"field": "a", "type": "ordinal"},
    "y": {"field": "b", "type": "quantitative"}
  }
}
```

Example - YAML specification

```vega-lite
data:
  values:
    - x: A
      y: 13
    - x: B
      y: 55
    - x: C
      y: 43
    - x: D
      y: 91      
    - x: E
      y: 81      
    - x: F
      y: 53      
    - x: G
      y: 19      
    - x: H
      y: 87      
    - x: I
      y: 52      
mark:
  bar
encoding:
  x:
    field: x
    type: ordinal
  y:
    field: y
    type: quantitative
```

Development

Compile and publish documentation to /docs.

npm run publish

Lint and Unit testing

npm test

Run demo

npm run demo

Resources

• Gulp
• Vega specification
• Vega-Lite specification
• Markdown guide