Node.js Pandoc Filters

A Node.js framework for building Pandoc filters

• Background
• Documentation
• Install
• Getting Started
• Examples
  • JavaScript
  • TypeScript
• Compatibility
• License

Background

Pandoc filters are executable scripts that Pandoc executes after compiling a document to Pandoc's proprietary AST. The pathway is as follows:

1. Pandoc compiles the source document to an AST written in JSON.
2. Pandoc streams (via stdin) the AST to each filter sequentially.
3. Each filter outputs (via stdout) an augmented AST for Pandoc to read.
4. Pandoc compiles the AST to the targeted format.

Documentation

Documentation is located here.

Install

You should install node-pandoc-filter globally for pandoc to execute Node.js-based filters:

npm install -g node-pandoc-filter

Getting Started

This package comes with two entry points:

• node-pandoc-filter/nodes: This is where all nodes (e.g. Str) and node-like creators (e.g. Attr) are imported from.
• node-pandoc-filter: Everything else.

The Math node is renamed to Formula as to not conflict with the internal Math object in JavaScript.

As stated previously, Pandoc filters are executable scripts, so you must use a hashbang at the top of each filter, targeting the specific method of execution. For example, #!/usr/bin/env node.

For TypeScript, you can use ts-node via it's ts-node-script executable rather than pre-compiling and using node. If you are compiling many document, this is NOT RECOMMENDED.

Examples

JavaScript

#!/usr/bin/env node
const { Str } = require("node-pandoc-filter/nodes");
const { toJSONFilter } = require("node-pandoc-filter");
const requestPromise = require("request-promise-native");

toJSONFilter({
  async Str(value) {
    const data = await requestPromise({ uri: value, json: true });
    return Str(data.places[0]["post code"]);
  },
});

TypeScript

#!/usr/bin/env ts-node-script
import { Str } from "node-pandoc-filter/nodes";
import { toJSONFilter } from "node-pandoc-filter";
import itFilters from "../utils/it-filters";

toJSONFilter({
  async Str(value) {
    return Str(value.toUpperCase());
  },
});

Compatibility

This package is compatible with

• Node.js >= v10
• Pandoc >= v1.17.2
  • If older compatibility is required, see pandoc-filter-node

License

Copyright © 2020 mu-io.

Licensed under MIT.