What We Learned Rewriting an Interactive Map Editor: Fabric.js, CORS, and 20,000 Lines of Legacy TypeScript

A story about how migrating an interactive office map editor turned into an engineering investigation involving Fabric.js, tainted canvas , and an architecture that's finally easy to extend. In most software projects, one sentence usually makes every developer nervous: "Let's rewrite this module from scratch." It often means months of development, regression risks, and endless architecture discussions. Our project was no different. We develop, a workspace management platform that allows companies to manage office spaces and book desks. One of its core features is an interactive office map editor, where administrators upload floor plans, place desks and meeting rooms, and publish maps for employees. Over the years, this editor slowly evolved into a real monolith. And the problem wasn't simply the number of lines of code. Where It All Started The editor dated back to the AngularJS era. The main component had gradually grown into a single file responsible for almost everything: loading maps working with Fabric.js CRUD operations keyboard shortcuts dialogs saving event handling The main editor component alone contained nearly 2,270 lines of code . Behind it lived another codebase — the map engine itself. Almost 20,000 lines of TypeScript spread across more than 230 files. One of the biggest architectural issues was an infinite rendering loop. fabric . util . requestAnimFrame (() => this . tick ()); Even when the user wasn't interacting with the editor, rendering continued forever. It worked. But every new feature became more expensive to build. Why We Decided to Rewrite It The motivation wasn't AngularJS itself. The real reason was business requirements. The product needed completely new capabilities: map drafts safe publishing high-quality printing multiple workspace modes easier support for new object types Every new feature pushed harder against the existing architecture. Eventually it became obvious: We weren't fighting individual bugs anymore. We were fighting the