I was searching a solution for an issue which is in my angular project, ng serve --watch was not detecting changes in some of the files.
And I got a solution which says use --poll=2000
It really worked.
But there are no clear information available about the function of flag poll.
In cases where Angular CLI is running in a shared directory on linux VM on a windows host the webpack dev server isn't detecting file changes from the host environment. (ex: Whenever a docker dev environment is running on a windows host.) This is solved by adding poll option to the webpack dev server configuration. By default when no poll interval is set watchpack will use native file system change detection. This change allows for setting the poll interval which will turn on polling.
Ref: https://github.com/angular/angular-cli/pull/1814#issuecomment-241854816
来源：https://stackoverflow.com/questions/51930195/what-is-the-function-of-poll-flag-in-cli