mdx-variables

This package enables you to read/extract variables that have been defined inside .mdx files. Find out more about the use cases and how to use this package here.

---

Getting Started

Install the package

npm install mdx-variables

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Using the package

1. Create an MDX file and define your variables

(mdx-example/pages/my-page.mdx)

const metadata = {
    author: 'Reece Charsville',
    date: new Date('2021-06-09T12:00:00.000Z'),
    tags: ['hello', 'world']
}


### This is my markdownX file
I can create my markdown file here using the metadata variable we defined.

<TagsComponent tags={metadata.tags} />
    
<Footer author={metadata.author} date={metadata.date} />

2. Now we can create our React component and extract the metadata

(mdx-example/blog-index.tsx)

import * as React from "react";
import { ReadVarFromMDX } from "mdx-variables";

type MDXTypes = {
    tags: Array<string>;
    author: string;
    date: Date;
}

const BlogIndex: React.FC = ({ children }): JSX.Element => {
    const [meta, setMeta] = React.useState<MDXTypes>();
    const [metaFromFile, setMetaFromFile] = React.useState<MDXTypes>();
    
    React.useEffect(() => {
        // This example uses a string value of the filename as the source
        const meta: MDXTypes = ReadVarFromMDX<MDXTypes>('metadata', 'pages', 'my-page.mdx');
        setMeta(meta);

        // This example uses an .mdx file buffer as the source
        const source: Buffer = fs.readFileSync('C:/mdx-example/pages/my-page.mdx');
        const metaFile: MDXTypes = ReadVarFromMDX<MDXTypes>('metadata', 'pages', source);
        setMetaFromFile(metaFile);
    }, []);
    
    return (
        <>
            <TagsComponent tags={meta?.tags} />
            <div>
                {children}
            </div>
            <div>{metaFile?.author} - {metaFile?.date}</div>
        </>
    );
};
export default BlogIndex;

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API

ReadVarFromMDX(variable, path, source)

Parameter	Type	Description
variable	string	The name of the variable that is defined inside the markdown file. Variable definitions must be defined using const or let.
path	string	The path from the project root to the directory where the markdown file is located.
source	string | Buffer	Either a string value representing the name of the markdown file including the .mdx extension "filename.mdx" or a file buffer for the mdx file.

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NOTE

If you are going to use this package with Next.js then you may want to use superjson. Next.js by default does not parse JS Date objects into component props. This means that variables inside the .mdx files containing JS Date objects can not be read/extracted without using superjson. You can read more about this Next.js limitation here.

To use superjson with Next.js

1. Install the following packages:

npm install babel-loader babel-plugin-superjson-next superjson

2. Create or edit the .babelrc file and add the following:

{
  presets: ["next/babel"],
  plugins: [
    "superjson-next"
  ]
}