parametrize.js

class SignupExp extends PlanOut.Experiment {
  //...other config
  assign(params, args) {
    params.set('signup_form_text', new PlanOut.Ops.Random.UniformChoice(choices=['Join Now', 'Sign up'], unit=userId));
    params.set('signup_nav_text', new PlanOut.Ops.Random.UniformChoice(choices=['Welcome to the Future', 'This product is great'], unit=userId));
  }
};

const exp = new SignupExp({userId: 'foo'});

const Parent = React.createClass({
  render() {
    return (
      <Parametrize experiment={exp} params={['signup_form_text', 'signup_nav_text']}>
        <SignupHeader />
        <SignupForm />
      </Parametrize>
    );
  }
});

const SignupHeader = withExperimentParams(React.createClass({
  render() {
    return (
      <div>
        {this.props.signup_nav_text}
      </div>
    );
  }
});

const SignupForm = withExperimentParams(React.createClass({
  render() {
    return (
      <div>
        {this.props.signup_form_text}
      </div>
    );
  }
});