WARNING - edit to Windows Registry, if you are not familiar with this browse online for best practices BEFORE changing anything.
To help speed you through browsing your JavaScript files (if your text editor does not open folders), you can preview your JS files in Windows Explorer. Check out
http://www.howtogeek.com/forum/topic/add-file-types-to-windows-7-preview-pane for instructions but essentially you:
1) Open regedit
2) Goto /HKEY_CLASSES_ROOT/.js
3) Add a string value named: PerceivedType
4) Add the following value data to the string PerceivedType: text
5) Close regedit
That is it. The next time you click on a JavaScript file, it will appear in the Windows preview pane.
To see an example of what those registry key looks like check out /HKEY_CLASSES_ROOT/.txt
Note, there are some open source solutions that add a "handler" to enable syntax coloring, in-place editing and such inside the preview pane but I recommend against those since they often lock a file for a period of time, preventing editing. If you need more features get a free text editor like Brackets or Atom.
Want more... the Windows explorer text preview pane settings use the Notepad text format. If you want a smaller font in the preview, simply open Notepad and set the Format > Font size down, to like 9 maybe. If your mouse has a wheel, you can change the preview text size by holding down the control button and turning the wheel (with your mouse over the preview pane).