@radicle/gray-matter/lib/defaults.js

Parse front-matter from a string or file. Fast, reliable and easy to use. Parses YAML front matter by default, but also has support for YAML, JSON, TOML or Coffee Front-Matter, with options to set custom delimiters. Used by metalsmith, assemble, verb and

'use strict';

const engines = require('./engines');
const utils = require('./utils');

module.exports = function(options) {
  const opts = Object.assign({}, options);

  // ensure that delimiters are an array
  opts.delimiters = utils.arrayify(opts.delims || opts.delimiters || '---');
  if (opts.delimiters.length === 1) {
    opts.delimiters.push(opts.delimiters[0]);
  }

  opts.language = (opts.language || opts.lang || 'yaml').toLowerCase();
  opts.engines = Object.assign({}, engines, opts.parsers, opts.engines);
  return opts;
};