How can I set up continuous integration and continuous deployment (CI/CD) for a Node.js application using Travis CI, including testing and deployment to Heroku or AWS Elastic Beanstalk?

To set up CI/CD with Travis CI for your Node.js application, start by creating a `.travis.yml` file in your repository. Then, do the steps below:

1. Define the build environment, install the dependencies, and specify the test scripts.
2. For deployment, add the deployment configurations to the same file. You can specify Heroku or AWS Elastic Beanstalk as the deployment targets.
3. Then, include any necessary authentication tokens securely using Travis CI's encrypted variables.
4. Ensure that your tests are comprehensive and cover critical parts of your application for a robust CI/CD pipeline.