Custom rule for markdownlint that disallows non-https links

http-link-warning.js

module.exports = {
  names: ["http-link-warning"],
  description: "Rule that reports an error for non-https links",
  tags: ["links"],
  function(params, onError) {
    params.tokens
      .filter((token) => token.type === "inline")
      .flatMap((token) => token.children)
      .filter(
        (token) =>
          token.type === "link_open" &&
          token.attrs.some(
            (attr) => attr[0] === "href" && attr[1].startsWith("http:")
          )
      )
      .forEach((token) =>
        onError({
          lineNumber: token.lineNumber,
          detail: token.attrs.find(
            (attr) => attr[0] === "href" && attr[1].startsWith("http:")
          )[1],
        })
      );
  },
};