AEM Debug .js & .java

aem-debug.txt

https://experienceleague.adobe.com/en/docs/experience-manager-learn/cloud-service/debugging/debugging-aem-sdk/remote-debugging

AEM Java code debug:-
Start AEM in debug mode run command
java -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=*:5005 -jar aem-author-p4502.jar

or 
Create a .bat file (debug-run.bat) in side of the author instance and put the script inside of the file.
java -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=*:5005 -jar aem-author-p4502.jar
To run the AEM in debug just double click on the .bat file.

Then Go to IntelliJ -> run -> edit configure -> Add -> Remote JVM Debug -> and do the small configuration and save it.

Now click on debug button and point the debugger points and reload the author instance page. But make sure reloadable page used the respective component to debug. 



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For js & css
inspect browser -> source -> CTRT+P 
Here, we can find all the related css & js. Just select break point in your js file and check with step over next.