Page.map.js and page.js suddenly generated on each pages

Hi Everybody,

If I am wrong, please let me know. But I have an issue.

Is there have an issue as my issue, which is suddenly file map.js and file .js generated on all of my ionic pages even provider file. As the screenshoot below, usually on the each page is only generated 3 file, right? which is cek.ts, cek.scss, cek.html (understand that ionic 3 have one more file it’s module.ts, but I deleted it because I still use modules on the app/root).

But after doing some change at the code then I see on the ionic serve, suddenly I got the new two files. Which is cek.map.js and cek.js.

My app still working and no error, but I think it will increase the size of apps.
image

and this is my package info:
ordova CLI: 6.5.0
Ionic CLI Version: 2.2.2
Ionic App Lib Version: 2.2.1
ios-deploy version: Not installed
ios-sim version: Not installed
OS: Windows 7
Node Version: v6.10.2
Xcode version: Not installed