Visual Studio Code is one of the most widely used development environments worldwide. It is engineered to make it easy and quick to design cloud- and web-based applications, using a vast plethora of extensible languages. The application is focused on maximizing code editing and unleashing the developer’s potential by providing useful shortcuts to provide quick access to all that is needed in a specific development context.

Visual Studio Code can be downloaded officially at https://code.visualstudio.com/ and, like most Integrated Development Environments (IDEs) nowadays, it has two different branches or deployment channels for its build: stable and insider. Together with these, it could also be used as a web application (https://vscode.dev/) or deployed on different platforms than Microsoft Windows, like iOS or Linux.

When you start Visual Studio Code, freshly installed locally, it will show you the typical Welcome page:

Figure 2.1: Visual Studio Code Welcome page

The Welcome page contains the following:

• Start: Shortcuts for creating and opening files and folders
• Recent: A list of recently opened files and folders
• Walkthroughs: A series of sliders that would help you tailor Visual Studio Code through your favorite settings such as background color themes, useful features enablement, and so on

The Welcome page is loaded whenever you run Visual Studio Code as a new window (Ctrl + Shift + N). It is possible to change this behavior by unchecking Show welcome page on startup or clicking File | Preferences | Settings and searching for Welcome page.

The Visual Studio Code environment is divided into five main areas:

• Code editor
• Status bar
• Activity bar
• Sidebar
• Panels area

Let’s look at each of them in the following sections, but if you want to check the documentation reference first, please visit https://code.visualstudio.com/docs/getstarted/userinterface.

Code editor

The code editor is where you write your code and where you spend most of your time. It is activated when creating a new file, or when opening an existing file or folder.

You can edit just one single file, or you can even load and work with multiple files at the same time, side by side, in editor groups:

Figure 2.2: Working on multiple files with editor groups

There are different ways to have multiple file views; three are mentioned here:

• Select a filename in the EXPLORER bar, then right-click and select Open to the Side (Ctrl + Enter).
• Press Ctrl + click on a filename in the EXPLORER bar.
• Press Ctrl + \ to split the editor into two parts.

Editor groups will accommodate several files, dividing the space equally between them. You can move through the different file editors by simply pressing Ctrl + 1, Ctrl + 2, Ctrl + 3, …, Ctrl + N.

Editor windows can be resized, reordered, and zoomed in/out according to your needs. To zoom in/out, press Ctrl + +/Ctrl + -, or View | Zoom in/Zoom out.

Visual Studio Code also provides an easy way of navigating between files with shortcuts. The quickest way is to press Ctrl + Tab. This will open the list of files that have been opened since Visual Studio Code started.

Last but not least, Ctrl + R could be considered the most used one. This will open a list of the recent files opened in the Command Palette.

Status bar

The status bar typically contains information about the currently selected file or folder. It also provides some actionable shortcuts:

Figure 2.3: Status bar shortcuts

From left to right, the status bar contains the following information:

• If Git is enabled, it will report version control information, such as, for example, the current branch.
• Number of errors and/or warnings detected in the current code.
• Cursor position (line position and column position).
• Indentation size and type (spaces or tabs).
• Encoding of the currently selected file.
• Line terminator: Carriage return (CR) and/or line feed (LF).
• Language used to process the code in the selected file. If you click on the language, a menu list will appear, and you should be able to change the processing programming language.
• Feedback button, which you can use to share your feedback about Visual Studio Code on Twitter/X or open a bug or feature implementation request.
• Notification icon: This shows the number of new notifications, which are typically related to product updates.

The status bar has a conventional colorization, and it changes depending on what’s processing. For example, it is purple when opening a new window or a new file, blue when opening a folder, orange when debugging, and so on.

Activity bar

This is on the left side of the workspace and contains shortcuts to the sidebar. If a shortcut is clicked, the sidebar that belongs to the tool that has been chosen becomes visible. Clicking again, or – for the shortcut lovers – pressing Ctrl + B, makes it disappear.

Manage

The Manage button is shown with a gear icon at the very bottom of the activity bar. If you click on it, a pop-up menu with a list of commands appears. These commands are used to tailor and customize Visual Studio Code at will, or to search for updates.

Command Palette

The Command Palette is one of the most important tools in Visual Studio Code. Its purpose is to give quick access to standard and extended commands. There are different ways to run the Command Palette:

• F1 (most used by all developers)
• Keyboard shortcut: Ctrl + Shift + P
• View | Command Palette
• The Manage button (the gear icon) | Command Palette

The Command Palette is not only good for showing menu commands but it can also perform other actions, such as installing extensions. You can browse through it to review the huge list of available commands. Commands are indexed and searchable. Just type a few letters to get a filtered list. It’s worth mentioning the long list of keyboard shortcuts that are available for most of these commands.

One very important thing to know about the Command Palette is the use of the > sign. When you press Ctrl + Shift + P, the Command Palette pops up with the > sign and shows the list of commands available. Take a look at the following screenshot:

Figure 2.4: Commands suggested by the Command Palette

If you remove the > symbol, Visual Studio Code uses the Command Palette to show a list of the recently opened files. The following screenshot shows this:

Figure 2.5: Recent files in the Command Palette

The power of this feature is that, without using the mouse, you can open the Command Palette, run a command, remove the > character, and select a file to edit (which is equivalent to using the shortcut Ctrl + P). That’s fantastic for development productivity.

Sidebar

The sidebar is the place where you will interact the most with the code editor. It is context-sensitive, and you will find five standard activities, each enabled by the corresponding icon in the view bar.

EXPLORER (Ctrl + Shift + E)

EXPLORER provides a structured and organized view of the folder and files that you are currently working with. The OPEN EDITORS sub-view contains the list of active files in the code editor. Below this section, there is another sub-view with the name of the folder that is open:

Figure 2.6: OPEN EDITORS sub-view

If you hover over the OPEN EDITORS sub-view, four action buttons will be shown: New (Ctrl + N), Toggle Vertical/Horizontal Editor Layout (Shift + Alt + O), Save All (Ctrl + K + S), and Close All Files (Ctrl + K or Ctrl + W):

Figure 2.7: OPEN EDITORS actions

Hovering over the folder name or any part of the sidebar (in this example, PACKTDEMOEXTENSION) will make four action buttons visible:

Figure 2.8: Example folder action buttons

From left to right, these are New File, New Folder, Refresh, and Collapse All.

Right-clicking on a folder or filename will open a context menu that shows common commands such as Reveal in Explorer (Shift + Alt + R), which opens the folder that contains the selected file. You can also copy the file path via Copy Path (Shift + Alt + C).

Further down in the EXPLORER bar, there is another section called OUTLINE. It gives a very useful tree view of members and types for a specific file, based on its language extension. If you have AL Language already installed, you might have this enabled. Take a look at the following screenshot:

Figure 2.9: OUTLINE tree view

This is a proficient option when you are developing complex objects and you want to jump into a specific area with just one click.

SEARCH (Ctrl + Shift + F)

This is a powerful tool for searching for and replacing text in files. It is possible to opt for a simple search with one or more keywords, and you can use wildcards such as * and ?. Alternatively, you can opt for creating a complex search based on regular expressions (regexes). There are also advanced options to include and/or exclude files or file types.

The SEARCH action bar is helpful for developers when searching the Where used field or variables in all files within an extension folder. Take a look at the following screenshot:

Figure 2.10: Searching extension files

Search outputs are listed in a tree view that lists all files containing the search keyword and shows a small piece of code related to the line that they belong to in the file. The keyword match is highlighted in the tree-view, as well as within the code editor. These can all be collapsed by clicking the Collapse All button.

It is possible to reset the search results by clicking the Clear Search Results button. It is also possible to turn sensitivity on/off and switch to regex view.

SOURCE CONTROL (Ctrl + Shift + G)

Visual Studio Code provides native integration with one of the most widely known source control management systems: Git. The basics and integration of Git will be discussed in Chapter 15, DevOps for Business Central.

DEBUG (Ctrl + Shift + D)

Visual Studio Code is not just a code editor for editing flat files. It also ships with an out-of-the-box integrated debugger framework that can be extended to debug different platforms and languages.

Visual Studio Code does not provide any debugging capability for Dynamics 365 Business Central per se. This comes embedded in the AL Language extension for Visual Studio Code, which extends the existing .NET core debugger. In Chapter 10, Debugging, we will discuss this argument in great detail.

EXTENSIONS (Ctrl + Shift + X)

The EXTENSIONS sidebar is used to browse the online marketplace for extensions for Visual Studio Code, which includes an ever-growing number of additional languages, debuggers, tools, helpers, and much more. AL Language is an extension for Visual Studio Code developed, maintained, and published by Microsoft. In the Visual Studio Code marketplace, you can also download several helpful extensions that extend (extensions for an extension) the AL Language extension and help Dynamics 365 Business Central developers be more efficient and productive and write code professionally and more proficiently. Take a look at the following screenshot, which shows typical Visual Studio Code extensions installed for Dynamics 365 Business Central:

Figure 2.11: Extensions in Business Central

In the EXTENSIONS bar, it is possible to search the online marketplace or install an extension manually. You can also see the list of installed, outdated, recommended, and disabled extensions and sort them according to different criteria.

It is also possible to perform actions on a single extension by right-clicking on it. An extension can be enabled, disabled, disabled per workspace (a workspace could be a project or a folder), and so on. There are also a couple of cool features related to Visual Studio Code extension deployments that are worth mentioning. The first is the ability to install another version of the extension (for example, click on the gear icon in the AL Language extension and choose Install Another Version…):

Figure 2.12: Installing extension versions

The second is the ability to deploy a pre-release instead of the official version. See below the button to deploy the pre-release for the AL Language extension:

Figure 2.13: Deploying a pre-release

This is very useful for Dynamics 365 Business Central developers, in case there are regression behaviors or bugs in higher-AL Language extension versions or the official release version. This is also useful when developments target a specific platform version.

Panels area

Visual Studio Code not only shows detailed analysis and information related to your code but also has access and display information coming from other sources such as Git, installed extensions, and debuggers. These outputs are logged into the Panels area, which, by default, is at the bottom, but could be easily moved to one side of the workspace using the Move Panel Right button, enabled by right-clicking on the panel’s title bar. It is possible to restore the original layout with the Move Panel to Bottom button, or even Hide Panel (Ctrl + J).

The Panels area is not visible by default. It is typically enabled and shown when the information needed is requested, such as when the debugger is enabled.

In the Panels area, there are four different windows (even though some extensions might add their own panels, such as GitLens): PROBLEMS, OUTPUT, DEBUG CONSOLE, and TERMINAL. Let’s examine them in the following sections.

PROBLEMS

With extension languages that have advanced editing features, such as AL, Visual Studio Code is able to identify code problems while typing. Problem lines have a specific colorization. There are three types of notifications: errors, warnings, and info. All of them can be shown in the PROBLEMS window. The following screenshot shows an example of the PROBLEMS window showing 4 errors and 3 warnings:

Figure 2.14: PROBLEMS window warnings

Typically, blocking errors are shown in red, while warnings are marked in yellow. Clicking any problem will open the file where the problem occurs, and the code that causes the problem will then be marked with a squiggly line in the problem color.

OUTPUT

The OUTPUT panel is the place where Visual Studio Code typically displays messages during or after command execution.

Because built-in tool actions and multiple extension commands can run concurrently, it is possible to make use of a drop-down box in the OUTPUT panel to change the view and see the output for each standard or extension-based command.

The following screenshot shows the OUTPUT window in the Panels area:

Figure 2.15: OUTPUT window messages

When working with Dynamics 365 Business Central extensions, the AL Language output window is selected automatically.

DEBUG CONSOLE

This is a special window used by native and extension-based debuggers, such as the AL language debugger, to display information about code execution. This window and its output will be analyzed in detail in Chapter 10, Debugging.

TERMINAL

Visual Studio Code allows us to execute commands in the same way as Command Prompt, directly from within the development environment. The Terminal session is based on PowerShell by default.

Now that we have all the elements that are related to Visual Studio Code in place, we can move on to the next section and deep-dive into the powerful editing features that it offers.

Visual Studio Code provides many of the features that you would expect from the best-in-class code editor. If you are familiar with Visual Studio, you might have noticed that some features have been engineered in a similar way.

Developed by developers for developers, Visual Studio Code has keyboard shortcuts for almost every editing command, giving you the option to edit code faster and completely forget about the mouse. Let’s study the most used features in the following sections.

Comment lines

Visual Studio Code provides out-of-the-box commands for text selection and professional editing in the Edit menu. The Edit menu also includes Toggle Line Comment, which adds a line comment for the selected line. This means that if you select 10 lines of code, Visual Studio Code will comment out the selected lines. The beauty of this command is that it works in reverse as well. If you select the 10 commented lines and press Toggle Line Comment, the comments will be magically removed. It is also possible to select Toggle Block Comment and revert this back (Shift + Alt + A).

For developers working with CSIDE, the old legacy language for on-premises Dynamics 365 Business Central, this command is the equivalent of Comment Selection (Shift + Ctrl + K) and Uncomment Selection (Shift + Ctrl + O).

Delimiter matching

Visual Studio Code can detect pairs of delimiters, such as brackets and parentheses. This feature is helpful if you want to delimit code blocks, and it kicks in when the mouse is placed near one of the delimiter pairs:

Figure 2.16: Delimiter brackets

Thanks to this feature, we can easily see that the brackets on lines 9 and 11 are matching. This is a simple example, but when working with code that uses multiple parentheses, it can be a helpful quality-of-life feature to quickly see which bracket corresponds to which.

Text selection

The Selection menu also has commands that relate to text selection, but most of them are used to move or duplicate lines of code above and below the selected line.

If you position the cursor near an AL function, variable, or constant, you can use Add Next Occurrence (Ctrl+ D), Add Previous Occurrence, or Select All Occurrences (Shift+ Ctrl+ D) to select occurrences of the selected item, and occurrences will be highlighted in a different color.

Code block folding

If you hover over line numbers in the code editor, a downward-pointing arrow will appear close to the initial part of a code block. Click on it to fold it, and a right arrow will appear. Click on this, and the code block unfolds:

Figure 2.17: Folded code on lines 5 and 18

The preceding screenshot shows two folded code blocks, depicted with right arrows.

Multiple cursors (or multi-cursors)

Each cursor operates independently. Alt + click will generate a secondary cursor at the desired position.

The most common development situation in which you want to go for multiple cursors is when you need to add or replace the same text in different positions but within the same source file. The following screenshot shows three cursors in action when editing the AL Language DataClassification property:

Figure 2.18: Multi-cursors on lines 10, 15, and 20

This is a great feature for AL language developers, especially when they have to write down the same sentence many times in the same place (for example, Caption or DataClassification in a table object and for each table field).

Mini-map

Sometimes, when working with very long files such as report definition language (RDL) files or codeunits, it is difficult to know where the pointer should be positioned – or is positioned – within a source file. Visual Studio Code has a fully fledged mini-map feature: a small preview of the source code file. The following is an example of an RDL:

Figure 2.19: Mini-map for an RDL file

The mini-map feature can be disabled/enabled through View | Appearance | Minimap, or by running the Command Palette (F1) and selecting View: Toggle Minimap.

Breadcrumbs

The Show Breadcrumbs command is available by clicking View | Appearance | Breadcrumbs or via the Command Palette (F1) and selecting View: Toggle Breadcrumbs. With AL files, you can click each element of the breadcrumb to inspect and explore the levels in the current object. There is a bit of text in the top-left corner of the code editor that can be expanded to easily double-check the definitions of properties, functions, fields, keys, and so on. If you click on an element in the expanded list, the cursor will jump to its primary definition, making code navigation quite fast and productive.

Figure 2.20: Viewing breadcrurmb elements

IntelliSense

In visual editors, IntelliSense is a word completion tool that appears as a pop-up list while you type. Visual Studio Code IntelliSense can provide smart suggestions, showing the definition and purpose – like online help – related to a specific element. The following screenshot shows IntelliSense in action:

Figure 2.21: IntelliSense word completion

IntelliSense is context-sensitive, and if you need to enable it directly without typing anything, just press Ctrl + spacebar. Depending on the context where the cursor is placed, IntelliSense will show all the items that can be used in that context. For example, inside a Table Field declaration, it will list all the specific field properties, such as Caption and CaptionML, while in an empty codeunit definition, it will show all the properties that are exposed by a codeunit object.

Word completion

Through the IntelliSense feature, the code editor in Visual Studio Code implements word completion for all native (such as JSON) and extension-based supported languages (such as AL). Just press Enter or Tab to insert the suggested word.

Go to definition

This is a super-cool, must-know feature. You can hover over a variable, constant, function, or whatever code element you want with the mouse, and if you press Ctrl, the word or identifier (known also as a symbol) will magically switch into a hyperlink.

If you click on the word while pressing Ctrl, you will be automatically redirected to the code that defines that word. Pressing Ctrl + hovering over a code element also enables the Go To Definition feature.

Other possible ways to enable this feature are as follows:

• Select a code element and press F12.
• Right-click on a code element and then select Go To Definition from the context menu.

Find all references

Find All References makes it very easy to parse how many times and where an object, a function, or any code element has been used across source code. You can simply right-click on any variable, function, or element name and then select Find All References, or use the keyboard shortcut Shift + Alt + F12.

When it’s enabled, the code editor will create a result list in the activity bar showing how many times it has been referenced, and in which object files and position(s). A shortcut icon is created in the sidebar called References. The following screenshot shows how to find all references in AL files for a specific variable:

Figure 2.22: Finding multiple referenes in source code

If you expand an occurrence in the references list on the left and click on a record, the code editor will open the file where it is referenced and position the cursor in editing mode, selecting the element searched in that file.

The references list can be cleared and refreshed, and you can collapse all the elements in it. If you clear the list, you can always run the previous search again, since the history is maintained for you.

Peek definition

Imagine that you have a large number of code files, and you need to edit the definition of a variable or field that you are currently using. With many other editors – or development environments – you most likely have to save all the files in text format, then search through all these code files and be sure to replace that variable name. This task not only can be annoying but can also distract you from the original code you were writing.

Visual Studio Code brilliantly solves this problem by providing the Peek feature, which can be enabled in different ways:

• Right-click a variable, field, or function name and select Peek Definition.
• Use the Alt + F12 keyboard shortcut.

An interactive pop-up window should appear, showing the source code that defines the selected element.

Figure 2.23: Using the Peek feature to locate a definition

The above screenshot shows the Peek Definition for a table source, bound to a dataitem element in a report. You can then see what has been written and directly edit it.

Renaming symbols

For a developer, it is very common to rename a variable, constant, field, or function. These coding elements are technically called symbols. Visual Studio Code provides a very powerful feature to rename symbols.

If you press F2 on the coding element that you wish to rename, or right-click and then select Rename Symbol, a small interactive popup appears in edit mode. There, you can write the new element name without using a distracting dialog window, allowing you to concentrate on your coding. All references to that code element will be renamed accordingly. The following screenshot shows renaming a procedure symbol reference:

Figure 2.24: Renaming a symbol

All the features shown so far are the most useful features provided by Visual Studio Code that support proficient code editing for AL developers. At this stage, then, it is important to take a closer look at the AL Language extension and see how to configure it to achieve more from the development environment.