Debugging Transpilation Issues

Common issues: when transpilation breaks

Runtime errors after transpilation usually mean: (1) missing polyfill, (2) unsupported syntax, (3) wrong target config, (4) plugin conflict.

Use browser dev tools with source maps

Enable source maps in build config to debug transpiled code. Errors point to original source, not generated code, making debugging easier.

Inspect transpiled output

Run Babel/SWC on a single file to see the output and spot problems.

# Babel
npx babel src/problem.js

# SWC
npx swc src/problem.js

# Save to file for detailed inspection
npx babel src/problem.js -o debug-output.js

Use source maps to trace errors back to source

Enable source maps in Babel/SWC config. Errors in the browser or runtime point to the original source, not the transpiled code.