unist-util-visit VS mdast

Although we are building a custom table of contents, we won't have to write everything from scratch. To separate the Markdown/MDX content from the front matter, we'll use the Gray-matter package. It is optional in case you don't have front matter in your Markdown files. To process the Markdown itself, we'll use the Remark package. We'll also need the unist-util-visit package for traversing node trees and mdast-util-to-string for getting the text content of a node.

For this example, we will use unist-util-visit to recursively inspect all the image nodes, and unist-util-generated to ensure we are not inspecting nodes that we have generated ourselves and do not belong to the doc.md.

contentlayer uses remark to parse the markdown in an mdast. We can now use remark plugins to modify the mdast. Then rehype comes into play and converts the mdast into a hast. rehype plugins can now modify the hast. Finally the hast is converted into react components.

remark parses and process the Markdown text, and converts it into an abstract syntax tree (AST). This tree is composed of unist nodes, which follow the Markdown Abstract Syntax Tree (mdast) structure.

Because we will be inspecting a mdast, which is a markdown abstract syntax tree built upon unist, we can take advantage of the many existing unist utilities to inspect our tree's nodes.