markdown-it-link-attributes/index.js

A markdown-it plugin to configure the attributes for links

"use strict";

// Adapted from https://github.com/markdown-it/markdown-it/blob/fbc6b0fed563ba7c00557ab638fd19752f8e759d/docs/architecture.md

function findFirstMatchingConfig(link, configs) {
  var i, config;
  var href = link.attrs[link.attrIndex("href")][1];

  for (i = 0; i < configs.length; ++i) {
    config = configs[i];

    // If there is a matcher function defined then call it
    // Matcher Function should return a boolean indicating
    // whether or not it matched. If it matched, use that
    // configuration, otherwise, try the next one.
    if (typeof config.matcher === "function") {
      if (config.matcher(href, config)) {
        return config;
      } else {
        continue;
      }
    }

    return config;
  }
}

function applyAttributes(idx, tokens, attributes) {
  Object.keys(attributes).forEach(function (attr) {
    var attrIndex;
    var value = attributes[attr];

    if (attr === "className") {
      // when dealing with applying classes
      // programatically, some programmers
      // may prefer to use the className syntax
      attr = "class";
    }

    attrIndex = tokens[idx].attrIndex(attr);

    if (attrIndex < 0) {
      // attr doesn't exist, add new attribute
      tokens[idx].attrPush([attr, value]);
    } else {
      // attr already exists, overwrite it
      tokens[idx].attrs[attrIndex][1] = value; // replace value of existing attr
    }
  });
}

function markdownitLinkAttributes(md, configs) {
  if (!configs) {
    configs = [];
  } else {
    configs = Array.isArray(configs) ? configs : [configs];
  }

  Object.freeze(configs);

  var defaultRender = md.renderer.rules.link_open || this.defaultRender;

  md.renderer.rules.link_open = function (tokens, idx, options, env, self) {
    var config = findFirstMatchingConfig(tokens[idx], configs);
    var attributes = config && config.attrs;

    if (attributes) {
      applyAttributes(idx, tokens, attributes);
    }

    // pass token to default renderer.
    return defaultRender(tokens, idx, options, env, self);
  };
}

markdownitLinkAttributes.defaultRender = function (
  tokens,
  idx,
  options,
  env,
  self
) {
  return self.renderToken(tokens, idx, options);
};

module.exports = markdownitLinkAttributes;