The instruction given at VS Code Command Line for launching a path are incorrect; the leading colon shown in the example doesn't work. However, launching with a backslash terminated directory name opens the specified directory as expected.
So, for example, 
code C:\Users\DAVE\Documents\Programming\Angular\StringCalculator\src\
opens the Visual Studio Code editor in directory C:\Users\DAVE\Documents\Programming\Angular\StringCalculator\src.
Important: The terminal backslash, though optional, is useful, as it makes clear that the intend is to open a directory, as opposed to a file. Bear in mind that file name extensions are, and always have been, optional.
Beware: The directory that gets appended to the PATH list is the \bin directory, and the shell command code launches a Windows NT Command script.
Hence, when incorporated into another shell script, code must be called or started if you expect the remainder of the script to run. Thankfully, I discovered this before my first test of a new shell script that I am creating to start an Angular 2 project in a local Web server, my default Web browser, and Visual Studio Code, all at once.
Following is my Angular startup script, adapted to eliminate a dependency on one of my system utilities that is published elsewhere, but not strictly required.
@echo off
goto SKIPREM
=========================================================================
Name:               StartAngularApp.CMD
Synopsis:           Start the Angular 2 application installed in a specified
                     directory.
Arguments:          %1 = OPTIONAL: Name of directory in which to application
                          is installed
Remarks:            If no argument is specified, the application must be in
                    the current working directory.
                    This is a completely generalized Windows NT command
                    script (shell script) that uses the NPM Angular CLI to
                    load an Angular 2 application into a Node development
                    Web server, the default Web browser, and the Visual
                    Studio Code text editor.
Dependencies:       Unless otherwise specified in the command line, the
                    application is created in the current working directory.
                    All of the following shell scripts and programs must be
                    installed in a directory that is on the Windows PATH
                    directory list.
                    1)  ShowTime.CMD
                    2)  WWPause.exe
                    3)  WWSleep.exe
                    4)  npm (the Node Package Manager) and its startup 
                        script, npm.cmd, must be accessible via the Windows
                        PATH environment string. By default, this goes into
                        directory C:\Program Files\nodejs.
                    5)  The Angular 2 startup script, ng.cmd, and the Node
                        Modules library must be installed for global access.
                        By default, these go into directory %AppData%\npm.
Author:             David A. Gray
Created:            Monday, 23 April 2017
-----------------------------------------------------------------------
Revision History
-----------------------------------------------------------------------
Date       By  Synopsis
---------- --- --------------------------------------------------------
2017/04/23 DAG Script created, tested, and deployed.
=======================================================================
:SKIPREM
echo BOJ %~0, version %~t0
echo.
echo -------------------------------------------------------
echo Displaying the current node.js version:
echo -------------------------------------------------------
echo.
node -v
echo.
echo -------------------------------------------------------
echo Displaying the current Node Package Manager version:
echo -------------------------------------------------------
echo.
call npm -v
echo.
echo -------------------------------------------------------
echo Loading Angular starter application %1
echo into a local Web server, the default Web browser, and
echo the Visual Studio Code text editor.
echo -------------------------------------------------------
echo.
if "%1" neq "" (
    echo.
    echo -------------------------------------------------------
    echo Starting the Angular application in directory %1
    echo -------------------------------------------------------
    echo.
    cd "%~1"
    call code %1\src\
) else (
    echo.
    echo -------------------------------------------------------
    echo Starting the Angular application in directory %CD%
    echo -------------------------------------------------------
    echo.
    call code %CD%\src\
)
call ng serve --open
echo.
echo -------------------------------------------------------
echo %~nx0 Done!
echo -------------------------------------------------------
echo.
Pause