A (mostly) painless guide to replacing your UI framework

Retail Zipline undertook the challenging task of replacing its existing UI frameworks, consolidating 650 views with a small team in under two months by following a structured approach. The project aimed to align with company goals without altering the existing visual design, thus minimizing noticeable changes for users and focusing on reducing technical debt. The team chose Bootstrap 4 to support IE 11 and avoid creating custom components, using a phased release strategy to manage the complexity of their Rails monolith application. They employed automation tools to streamline the migration process, including a custom library to facilitate class name replacements, and relied on feature flags to integrate changes without impacting users. By creating a new views folder and organizing tasks with weekly goals, the team maintained focus and efficiency, avoiding unnecessary daily meetings. The project concluded with a cleanup phase to remove outdated views and consolidate framework conventions, ensuring a streamlined and cohesive new version of the application.