Function getReplacePlugin

build-system/babel-config/helpers.js:33–83

* Computes options for minify-replace and returns the plugin object. * * @param {!Object=} opt_overrides overrides for BUILD_CONSTANTS * @return {Array }

(opt_overrides)

 * @return {Array<string|Object>}
 */
function getReplacePlugin(opt_overrides) {
  /**
   * @param {string} identifierName the identifier name to replace
   * @param {boolean|string} value the value to replace with
   * @return {!Object} replacement options used by minify-replace plugin
   */
  function createReplacement(identifierName, value) {
    const replacement =
      typeof value === 'boolean'
        ? {type: 'booleanLiteral', value}
        : {type: 'stringLiteral', value};
    return {identifierName, replacement};
  }

  const constants = Object.assign({}, BUILD_CONSTANTS, opt_overrides);
  const replacements = Object.entries(constants).map(([ident, val]) =>
    createReplacement(ident, val)
  );

  const experimentConstant = getExperimentConstant();
  if (experimentConstant) {
    replacements.push(createReplacement(experimentConstant, true));
  }

  // default each experiment flag constant to false
  Object.keys(experimentsConfig).forEach((experiment) => {
    const experimentDefine =
      experimentsConfig[experiment]['define_experiment_constant'];
    const flagExists = (element) =>
      element['identifierName'] === experimentDefine;
    // only add default replacement if it already doesn't exist in array
    if (experimentDefine && !replacements.some(flagExists)) {
      replacements.push(createReplacement(experimentDefine, false));
    }
  });

  // default each backup experiment constant to the customized value
  const experimentsConstantBackupEntries = Object.entries(
    experimentsConstantBackup
  );
  for (const [experimentDefine, value] of experimentsConstantBackupEntries) {
    const flagExists = (element) =>
      element['identifierName'] === experimentDefine;
    // only add default replacement if it already doesn't exist in array
    if (experimentDefine && !replacements.some(flagExists)) {
      replacements.push(createReplacement(experimentDefine, !!value));
    }
  }

  return ['minify-replace', {replacements}];
}

/**
 * Returns a Babel plugin that replaces the global identifier with the correct