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VS Code extension: package.json

package.json is an extension's manifest file. This file is located in the root of the extension's directory structure.
Apparently, package.json is a concept of Yarn where it is used to describe a package.
The four required fields in package.json are
name All lowercase. Compare with displayName.
version In Semantic versioning format (maj.min.pch).
publisher which identifies the identity that is allowed to publish an extension to the Visual Studio Code Marketplace.
engines
Thus, a minimal package.json could be: 
{
   "name"       : "basic-extension"    ,
   "version"    : "0.0.1"              ,
   "publisher"  : "tq84"               ,
   "engines"    :{"vscode": "^1.32.0" },
    …
}
Other important or interesting fields are
main The extension's main module, i. e. the name of a JavaScript file, relative to the extension's root. This module must expose the function activate() (which is called when the first event listed in activationEvents is triggerd). The .js suffix can be omitted (in fact, it even seems to be recommended because it is assumed to be a JavaScript file anyway). browser is the same, but for VS Code running in the browser.
activationEvents List of activation events. The special event * is fired when VS Code is started. When one of the given activation events are triggered, the extension is activated, i. e. the activate() function in the extension's main module is called. activate() is not called multiple times.
contributes Description of the functionality that is provided («contributed…) by the extension.
engines.vscode The minimum VS Code API version that the extension requires
dependencies
repository
license For example "MIT". It's possible to refer to a license file in the root of the extension ("See license in LICENSE")
categories A list of strings. Permitted values are: Programming Languages, Snippets, Linters, Themes, Debuggers, Formatters, Keymaps, SCM Providers, Other, Extension Packs, Language Packs, Data Science, Machine Learning, Visualization, Notebooks, Education and Testing. Compare with keywords.
displayName Extension's name in the market place. Compare with name and description.
keywords A list of up to 5 keywords, used to find the extension on the Marketplace. Campare with cateogries.
publisher dot name (tq84.demo-extension) is the extension's unique ID, used by VS Code to identify the extension.
package.json must be stored as a «pure» JSON file: comments are (as per strict JSON specification) not allowed.

activationEvents

activationEvents is an array whose elements define when an extension is activated.
Possible values for the elements of activationEvents include
* VS Code starts up
onStartupFinished After VS Code is started up. Similar to *, but with the intension not to slow down the starting up process.
onLanguage:xyz a file whose language ID is xyz is opened
onCommand:…
workspaceContains:**/pattern.* A folder is opened that contains a file whose name matches the given pattern.
onDebug before a debug session is started
onDebugInitialConfigurations activation is just before the provideDebugConfigurations method of the DebugConfigurationProvider is called.
onDebugResolve:type activation is just before the resolveDebugConfiguration method of the DebugConfigurationProvider is called.
onFileSystem:scheme A file with the given scheme (sftp, ftp, ssh …) is opened
onView:viewID A view with the given ID is opened
onUri
onWebviewPanel

contributes

configuration Specification of extension settings that the user can modify.
configurationDefaults Overwrite default editor configurations
commands add a titled command (and optionally an icon, category and enabled state). Such commands show up in the Command Palette (ctrl+shift+p) and possibly in other menus, too.
menus
submenus
keybindings Assigns a command to combination of keys being pressed (shortcut key)
languages Defines a «new» language (id?)
debuggers
breakpoints
grammars A TextMate grammar
themes Color theme
icons
iconThemes File icon themes, which are shown next to file names
productIconThemes
snippets
jsonValidation
views
viewsWelcome
viewsContainers
walkthroughs intended to introduce an extension to a user
problemMatchers
problemPatterns
taskDefinitions
colors
typescriptServerPlugins
resourceLabelFormatters
customEditors
contributes.con
terminal
semanticTokenModifiers
semanticTokenScopes
semanticTokenTypes

Links

The extension manifest reference has a list of allowed field-names in package.json.

Index