How to enable js debug in popup window

If there is no redirect,
1. Chrome Settings: check "Auto-open DevTools for popups"
2. In Devtools, add breakpoint in source codes
(Chrome remembers the breakpoint as long as DevTools open)

If there is redirect, follow below steps:
1. Chrome Settings: check "Auto-open DevTools for popups"
2. In js source code, add 'debugger' where you want to break
3. When do js uglify, don't drop debugger
    compress: {
        drop_debugger: false
    }