gatsby-node.js

const path = require('path');
const generateBabelConfig = require('gatsby/dist/utils/babel-config');

exports.onCreateNode = ({ node, boundActionCreators, getNode }) => {
  const { createNodeField } = boundActionCreators;
  let slug;
  if (node.internal.type === 'MarkdownRemark') {
    const fileNode = getNode(node.parent);
    const { dir, name } = path.parse(fileNode.relativePath);
    if (name !== 'index' && dir !== '') {
      slug = `/${dir}/${name}/`;
    } else if (dir === '') {
      slug = `/${name}/`;
    } else {
      slug = `/${dir}/`;
    }

    // Add slug as a field on the node.
    createNodeField({ node, name: 'slug', value: slug });
  }
};

exports.createPages = ({ graphql, boundActionCreators }) => {
  const { createPage } = boundActionCreators;

  return new Promise((resolve, reject) => {
    const Article = path.resolve('src/templates/Article.jsx');
    // Query for all markdown 'nodes' and for the slug we previously created.
    resolve(
      graphql(
        `
        {
          allMarkdownRemark {
            edges {
              node {
                fields {
                  slug
                }
              }
            }
          }
        }
      `
      ).then(result => {
        if (result.errors) {
          console.log(result.errors);
          reject(result.errors);
        }

        // Create article pages.
        result.data.allMarkdownRemark.edges.forEach(edge => {
          createPage({
            path: edge.node.fields.slug,
            component: Article,
            context: {
              slug: edge.node.fields.slug
            }
          });
        });

        return;
      })
    );
  });
};


exports.modifyWebpackConfig = ({ config, stage }) => {
  const program = {
    directory: __dirname,
    browserslist: ['> 1%', 'last 2 versions', 'IE >= 9']
  };

  return generateBabelConfig(program, stage).then(babelConfig => {
    config.removeLoader('js').loader('js', {
      test: /\.jsx?$/,
      exclude: modulePath => {
        return (
          /node_modules/.test(modulePath) &&
          !(/node_modules\/react\-freecodecamp\-search/).test(modulePath)
        );
      },
      loader: 'babel',
      query: babelConfig
    });
  });
};