Gulp returns error: EPERM: operation not permitted, chmod <directoryName>问题解决办法

I was working on a script that updated sitemap.xml in the public directory and to do this, it needed permission for writing to the Public directory of Laravel. So I ran the following command in terminal:

sudo chown -R www-data:www-data public

Everything seemed to be fine until I ran 'gulp' command in terminal to compile my SASS and JS files and got the following error:

EPERM: operation not permitted, chmod <path>/script.jsat Error (native)

OR

Error: EACCES: permission denied, open <path>/navigation.css'at Error (native)

I hope I didn't screw up the environment by doing chown :S Anyone can help me please? My website was almost ready:/