when i change in js files changes not reflect.

Hi,

when i modify in js files (vendor\flarum\core\js\src\forum\components\DiscussionList.js) changes not reflect.

Please help me to solve this

try to run php flarum cache:clear

The JS source files are not in use in Flarum. Here are your options:

Recommended: Create a (local) extender to impact the JS so that you can still upgrade in the future.
You can edit the said file, then recompile the JS again so that it is picked up by flarum.

Compilation is done using npm. Check our docs on extend to see how exactly to work with the javascript frontend.