build.js

'use strict';

// Do this as the first thing so that any code reading it knows the right env.
process.env.NODE_ENV = 'production';

// Makes the script crash on unhandled rejections instead of silently
// ignoring them. In the future, promise rejections that are not handled will
// terminate the Node.js process with a non-zero exit code.
process.on('unhandledRejection', err => {
  throw err;
});

// Ensure environment variables are read.
require('../config/env');

const chalk = require('chalk');
const fs = require('fs-extra');
const path = require('path');
const url = require('url');
const webpack = require('webpack');
const config = require('../config/webpack.config.prod');
const paths = require('../config/paths');
const checkRequiredFiles = require('react-dev-utils/checkRequiredFiles');
const FileSizeReporter = require('react-dev-utils/FileSizeReporter');

const measureFileSizesBeforeBuild = FileSizeReporter.measureFileSizesBeforeBuild;
const printFileSizesAfterBuild = FileSizeReporter.printFileSizesAfterBuild;
const useYarn = fs.existsSync(paths.yarnLockFile);

// Warn and crash if required files are missing
if (!checkRequiredFiles([paths.appHtml, paths.appIndexJs])) {
  process.exit(1);
}

// First, read the current file sizes in build directory.
// This lets us display how much they changed later.
measureFileSizesBeforeBuild(paths.appBuild).then(previousFileSizes => {
  // Remove all content but keep the directory so that
  // if you're in it, you don't end up in Trash
  fs.emptyDirSync(paths.appBuild);

  // Start the webpack build
  build(previousFileSizes);

  // Copy data folder
  copyDataFolder();

  // Copy scss files from /src to /build
  copyScss();
});

// Print out errors
function printErrors(summary, errors) {
  console.log(chalk.red(summary));
  console.log();
  errors.forEach(err => {
    console.log(err.message || err);
    console.log();
  });
}

// Create the production build and print the deployment instructions.
function build(previousFileSizes) {
  console.log('Creating an optimized production build...');

  let compiler;
  try {
    compiler = webpack(config);
  } catch (err) {
    printErrors('Failed to compile.', [err]);
    process.exit(1);
  }

  compiler.run((err, stats) => {
    if (err) {
      printErrors('Failed to compile.', [err]);
      process.exit(1);
    }

    if (stats.compilation.errors.length) {
      printErrors('Failed to compile.', stats.compilation.errors);
      process.exit(1);
    }

    if (process.env.CI && stats.compilation.warnings.length) {
      printErrors(
        'Failed to compile. When process.env.CI = true, warnings are treated as failures. Most CI servers set this automatically.',
        stats.compilation.warnings
      );
      process.exit(1);
    }

    console.log(chalk.green('Compiled successfully.'));
    console.log();

    console.log('File sizes after gzip:');
    console.log();
    printFileSizesAfterBuild(stats, previousFileSizes);
    console.log();
  });
}

function copyDataFolder() {
  fs.copySync(path.resolve(__dirname, '../node_modules/vega-datasets'), path.resolve(paths.appBuild, 'datasets'), {
    dereference: true,
  });
}

// Copy scss files from /src/components/ to /build/components/ for external app to use Voyager components
function copyScss() {
  fs.copySync(path.resolve(__dirname, '../src/components'), path.resolve(__dirname, '../build/components'), {
    dereference: true,
    filter: (path) => {
      if (fs.lstatSync(path).isDirectory()) {
        return true;
      } else {
        return path.endsWith('.scss');
      }
    }
  });
}