How can I open data/data/com.termux/files I am unable to access com.termux/files folder. I want to access it because I want to do a change in writer.js files.

I tried cd.. and cd - codes to go back to files folder from home folder.
In order to get to the Termux files folder, you have to CD to the entire path name like this. 

cd /data/data/com.termux/files


From there can cd into the usr folder and where ever you want to go. Once you find writer.js you can edit it using nano which comes with Termux. Enter nano writer.js, make your edits and the use CTRL O to save it and CTRL X to exit nano.

Then you can get back to your home directory with:

cd ~