function setup()

in src/Worker.js [54:100]

• 42 lines of code
• 7 McCabe index (conditional complexity)

function setup(tr, babel) {
  if (babel === 'babel') {
    const presets = [];
    if (presetEnv) {
      presets.push([
        presetEnv.default,
        {targets: {node: true}},
      ]);
    }
    presets.push(
      /\.tsx?$/.test(tr) ?
        require('@babel/preset-typescript').default :
        require('@babel/preset-flow').default
    );

    require('@babel/register')({
      babelrc: false,
      presets,
      plugins: [
        require('@babel/plugin-proposal-class-properties').default,
        require('@babel/plugin-proposal-nullish-coalescing-operator').default,
        require('@babel/plugin-proposal-optional-chaining').default,
        require('@babel/plugin-transform-modules-commonjs').default,
      ],
      extensions: [...DEFAULT_EXTENSIONS, '.ts', '.tsx'],
      // By default, babel register only compiles things inside the current working directory.
      // https://github.com/babel/babel/blob/2a4f16236656178e84b05b8915aab9261c55782c/packages/babel-register/src/node.js#L140-L157
      ignore: [
        // Ignore parser related files
        /@babel\/parser/,
        /\/flow-parser\//,
        /\/recast\//,
        /\/ast-types\//,
      ],
    });
  }

  const module = require(tr);
  transform = typeof module.default === 'function' ?
    module.default :
    module;
  if (module.parser) {
    parserFromTransform = typeof module.parser === 'string' ?
      getParser(module.parser) :
      module.parser;
  }
}