Official Plugin

gatsby-remark-autolink-headers

Adds GitHub-style hover links to headers in your markdown files when they’re rendered.

This is a sub-plugin for gatsby-transformer-remark. As demoed below, add this plugin to the options of gatsby-transformer-remark.

Install

npm install gatsby-remark-autolink-headers

How to use

// In your gatsby-config.js
module.exports = {
  plugins: [
    {
      resolve: `gatsby-transformer-remark`,
      options: {
        plugins: [`gatsby-remark-autolink-headers`],
      },
    },
  ],
}

Please note: If you are using gatsby-remark-prismjs, make sure that it’s listed after this plugin. Otherwise, you might face an issue with redundant details.

// good
{
  resolve: `gatsby-transformer-remark`,
  options: {
    plugins: [
      `gatsby-remark-autolink-headers`,
      `gatsby-remark-prismjs`,
    ],
  },
}

// bad
{
  resolve: `gatsby-transformer-remark`,
  options: {
    plugins: [
      `gatsby-remark-prismjs`, // should be placed after `gatsby-remark-autolink-headers`
      `gatsby-remark-autolink-headers`,
    ],
  },
}

Options

offsetY: Signed integer. Vertical offset value in pixels (optional)
icon: SVG shape inside a template literal or boolean false. Set your own svg or disable icon (optional)
className: String. Set your own class for the anchor (optional)
maintainCase: Boolean. Maintains the case for markdown header (optional)
removeAccents: Boolean. Remove accents from generated headings IDs (optional)
enableCustomId: Boolean. Enable custom header IDs with {#id} (optional)
isIconAfterHeader: Boolean. Enable the anchor icon to be inline at the end of the header text (optional)
elements: String array. Specify which type of header tags to link (optional)

// In your gatsby-config.js
module.exports = {
  plugins: [
    {
      resolve: `gatsby-transformer-remark`,
      options: {
        plugins: [
          {
            resolve: `gatsby-remark-autolink-headers`,
            options: {
              offsetY: `100`,
              icon: `<svg aria-hidden="true" height="20" version="1.1" viewBox="0 0 16 16" width="20"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg>`,
              className: `custom-class`,
              maintainCase: true,
              removeAccents: true,
              isIconAfterHeader: true,
              elements: [`h1`, `h4`],
            },
          },
        ],
      },
    },
  ],
}

Please note: The enableCustomId option is not compatible with gatsby-plugin-mdx as the syntax is invalid in MDX v2. You should use rehype-slug-custom-id instead.

How to style the anchor link

By default, the anchor link has a class of anchor (see className option to change this name) on the element but has no additional styling. To make it fit your website, you’ll have to write some CSS to change the appearance.

In your CSS you can specify this element, in this instance the anchor tag will appear red:

a.anchor {
  fill: "red";
}

Please note: There are a variety of approaches to styling your Gatsby site, see styling documentation for more detail.