Build application with source map:
"build": "ng build --prod --source-map",
But now the source maps would be revealed in production. To hide them we simply create another folder in our dist
and move the source maps to it.
"postbuild": "mkdir dist/sourceMapInspector/sourceMaps; mv dist/sourceMapInspector/*.map dist/sourceMapInspector/sourceMaps"
In production, we can find the source map by manully enter the source map url on server, then use 'Add source map' from Chrome dev tool to add source map in our production app.
Then we can debug it as normal as in the developement env.