The problem is: I have to update a js file, say in the dir public_html/js/aa.js. also I have to upate it in another dir, like public_html2/js/aa.js
However aftering changing the file, one works the other still the same.
After exploring for a while, the solutiio is: just change the js file name and change the name where the file is used.
The problem was caused by cache. We can file more by looking at the page: