The walkthrough details the process of creating a type-safe REST API using Node.js and TypeScript, integrating feature flags with Split to facilitate controlled feature delivery and A/B testing. It emphasizes the advantages of using TypeScript, a type-safe superset of JavaScript, to enhance the development experience by providing type safety and facilitating the creation of scalable applications. The tutorial guides users through setting up a TypeScript development environment, building an Express server, creating a feature flag with Split for a GET /timezones endpoint, and utilizing middleware for dynamic feature management. It also covers the use of declaration files, the benefits of using feature flags in real-world applications, and how to manage code branching with feature flags for a consistent user experience. The example demonstrates how to apply these techniques in a Node.js environment to improve software development practices and enhance application reliability and user experience.