How do I load a markdown file into a react component?

A full working example with react-markdown:

import React, { Component } from 'react'
import ReactMarkdown from 'react-markdown'
import termsFrPath from './Terms.fr.md'

class Terms extends Component {
  constructor(props) {
    super(props)

    this.state = { terms: null }
  }

  componentWillMount() {
    fetch(termsFrPath).then((response) => response.text()).then((text) => {
      this.setState({ terms: text })
    })
  }

  render() {
    return (
      <div className="content">
        <ReactMarkdown source={this.state.terms} />
      </div>
    )
  }
}

export default Terms

You should use react-markdown instead of the accepted answer, this solution doesn't use dangerouslySetInnerHTML.

App.js

import React, { Component } from 'react';
import AppMarkdown from './App.md';
import ReactMarkdown from 'react-markdown';

class App extends Component {

  constructor() {
    super();
    this.state = { markdown: '' };
  }

  componentWillMount() {
    // Get the contents from the Markdown file and put them in the React state, so we can reference it in render() below.
    fetch(AppMarkdown).then(res => res.text()).then(text => this.setState({ markdown: text }));
  }

  render() {
    const { markdown } = this.state;
    return <ReactMarkdown source={markdown} />;
  }
}

export default App;

App.md

# React & Markdown App
* Benefits of using React... but...
* Write layout in Markdown!

markdown-to-jsx provides very efficeint functionality to interact with markdown in React component.

It allows replacing/overriding of any HTML element with your Custom Component for markdown, here is the doc.

import React, { Component } from 'react'
import Markdown from 'markdown-to-jsx';
import README from './README.md'

class PageComponent extends Component {
  constructor(props) {
    super(props)

    this.state = { md: "" }
  }

  componentWillMount() {
    fetch(README)
      .then((res) => res.text())
      .then((md) => {
        this.setState({ md })
      })
  }

  render() {

    let { md } = this.state

    return (
      <div className="post">
        <Markdown children={md}/>
      </div>
    )
  }
}

export default PageComponent

Edit 2nd Aug'21

Functional Component

const PageComponent = ()=> {

    let [ content, setContent] = useState({md: ""});

    useEffect(()=> {
        fetch(README)
            .then((res) => res.text())
            .then((md) => {
                setContent({ md })
            })
    }, [])

    return (
      <div className="post">
        <Markdown children={content.md}/>
      </div>
    )
}

I use marked (GitHub).

I first import it like this:

import marked from "marked";

I then fetch my *.md file within React's componentDidMount event and store it in my component's state using marked(text) (where text is the response):

componentDidMount() {
  const readmePath = require("./Readme.md");

  fetch(readmePath)
    .then(response => {
      return response.text()
    })
    .then(text => {
      this.setState({
        markdown: marked(text)
      })
    })
}

...and finally I render it on the page using the dangerouslySetInnerHTML attribute:

render() {
  const { markdown } = this.state;

  return (
    <section>
      <article dangerouslySetInnerHTML={{__html: markdown}}></article>
    </section>
  )
}