Transform your codebase without breaking a sweat
summary
Etsy converts CSS to SCSS and migrates inline JS toward AMD by writing automated AST transforms that find and replace calls like underscore.bind and jQuery.proxy with function.prototype.bind after dropping an MDN polyfill. The pipeline uses esprima plus traversal and codegen, adds beaconing instrumentation in production, performs a soft rollout, watches metrics and error logs, and then removes shims and experiment flags — the automated refactor and rollout report low breakage and successful cleanup.
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chapters (10)
- 0:00Managing codebase growth
- 2:25The role of infrastructure
- 3:49A framework for transformation
- 5:57Identifying code friction
- 8:40Automating via ASTs
- 10:46Implementing the transformation
- 13:52Verification and monitoring
- 17:05Cleanup and finalization
- 19:42Lessons and best practices
- 22:53Q&A session
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