node_modules/log4js/lib/appenders/stdout.js

function stdoutAppender(layout, timezoneOffset) {
  return (loggingEvent) => {
    process.stdout.write(`${layout(loggingEvent, timezoneOffset)}\n`);
  };
}

function configure(config, layouts) {
  let layout = layouts.colouredLayout;
  if (config.layout) {
    layout = layouts.layout(config.layout.type, config.layout);
  }
  return stdoutAppender(layout, config.timezoneOffset);
}

exports.configure = configure;