It can be helpful for developers to look into the source code of files, with the preview of the Windows File Explorer, without opening all the files.

Source Code Preview with File Explorer

Specifying File Handlers for File Name Extensions with add the registry classes keys to preview files for php, ps1, py, css, vbs, shell scripts and more in File Explorer with just expanding it.

To do this, open a command prompt with elevated rights as an administrator and add the following lines.

REG ADD "HKCR\.sh" /v "PerceivedType" /t REG_SZ /d "text" /f
REG ADD "HKCR\.sh" /ve /t REG_SZ /d "txtfile" /f
REG ADD "HKCR\.sh" /v "Content Type" /t REG_SZ /d "text/plain" /f
REG ADD "HKCR\.sh\PersistentHandler" /ve /t REG_SZ /d "{5e941d80-bf96-11cd-b579-08002b30bfeb}" /f

REG ADD "HKCR\.php" /v "PerceivedType" /t REG_SZ /d "text" /f
REG ADD "HKCR\.php" /ve /t REG_SZ /d "txtfile" /f
REG ADD "HKCR\.php" /v "Content Type" /t REG_SZ /d "text/plain" /f
REG ADD "HKCR\.php\PersistentHandler" /ve /t REG_SZ /d "{5e941d80-bf96-11cd-b579-08002b30bfeb}" /f

REG ADD "HKCR\.py" /v "PerceivedType" /t REG_SZ /d "text" /f
REG ADD "HKCR\.py" /ve /t REG_SZ /d "txtfile" /f
REG ADD "HKCR\.py" /v "Content Type" /t REG_SZ /d "text/plain" /f
REG ADD "HKCR\.py\PersistentHandler" /ve /t REG_SZ /d "{5e941d80-bf96-11cd-b579-08002b30bfeb}" /f

REG ADD "HKCR\.ps1" /v "PerceivedType" /t REG_SZ /d "text" /f
REG ADD "HKCR\.ps1" /ve /t REG_SZ /d "txtfile" /f
REG ADD "HKCR\.ps1" /v "Content Type" /t REG_SZ /d "text/plain" /f
REG ADD "HKCR\.ps1\PersistentHandler" /ve /t REG_SZ /d "{5e941d80-bf96-11cd-b579-08002b30bfeb}" /f

REG ADD "HKCR\.css" /v "PerceivedType" /t REG_SZ /d "text" /f
REG ADD "HKCR\.css" /ve /t REG_SZ /d "txtfile" /f
REG ADD "HKCR\.css" /v "Content Type" /t REG_SZ /d "text/plain" /f
REG ADD "HKCR\.css\PersistentHandler" /ve /t REG_SZ /d "{5e941d80-bf96-11cd-b579-08002b30bfeb}" /f

REG ADD "HKCR\.vbs" /v "PerceivedType" /t REG_SZ /d "text" /f
REG ADD "HKCR\.vbs" /ve /t REG_SZ /d "txtfile" /f
REG ADD "HKCR\.vbs" /v "Content Type" /t REG_SZ /d "text/plain" /f
REG ADD "HKCR\.vbs\PersistentHandler" /ve /t REG_SZ /d "{5e941d80-bf96-11cd-b579-08002b30bfeb}" /f

Now just activate the preview in Windows File Explorer.