npm install -g yo generator-code

yo code

{
  "name": "demo1",
  "displayName": "demo1",
  "description": "my demo1",
  "version": "0.0.1",
  "publisher": "name1",
  "engines": {
    "vscode": "^1.28.0"
  },
  "categories": [
    "Other"
  ],
  "activationEvents": [
    "onCommand:extension.sayHello"
  ],
  "main": "./extension",
  "contributes": {
    "commands": [
      {
        "command": "extension.sayHello",
        "title": "Hello World"
      }
    ]
  },
  "scripts": {
    "postinstall": "node ./node_modules/vscode/bin/install",
    "test": "node ./node_modules/vscode/bin/test"
  },
  "devDependencies": {
    "typescript": "^2.6.1",
    "vscode": "^1.1.21",
    "eslint": "^4.11.0",
    "@types/node": "^8.10.25",
    "@types/mocha": "^2.2.42"
  }
}

// The module 'vscode' contains the VS Code extensibility API
// Import the module and reference it with the alias vscode in your code below
const vscode = require('vscode');

// this method is called when your extension is activated
// your extension is activated the very first time the command is executed
function activate(context) {

  // Use the console to output diagnostic information (console.log) and errors (console.error)
  // This line of code will only be executed once when your extension is activated
  console.log('Congratulations, your extension "demo1" is now active!');

  // The command has been defined in the package.json file
  // Now provide the implementation of the command with  registerCommand
  // The commandId parameter must match the command field in package.json
  let disposable = vscode.commands.registerCommand('extension.sayHello', function () {
    // The code you place here will be executed every time your command is executed

    // Display a message box to the user
    vscode.window.showInformationMessage('Hello World!');
  });

  context.subscriptions.push(disposable);
}
exports.activate = activate;

// this method is called when your extension is deactivated
function deactivate() {
}
exports.deactivate = deactivate;

npm install -g vsce

$ cd demo1
$ vsce publish
Publishing demo1@0.0.1...
Successfully published demo1@0.0.1!