Window API - Visual Studio Code

The Window API (vscode.window) provides access to VS Code’s UI, including editors, terminals, status bar, notifications, and user input dialogs. It’s one of the most frequently used namespaces in extension development.

Overview

The window namespace enables extensions to:

Show messages and dialogs to users
Create and manage webview panels
Access active editors and terminals
Display progress indicators
Create custom UI components (quick picks, input boxes)
Manage output channels and status bar items

Active Editors

Access Active Editor

import * as vscode from 'vscode';

// Get the currently active text editor
const editor = vscode.window.activeTextEditor;

if (editor) {
  const document = editor.document;
  const selection = editor.selection;
  
  // Get selected text
  const text = document.getText(selection);
  console.log('Selected text:', text);
}

Editor Properties

activeTextEditor

The currently focused text editor or undefined if none is active.

const editor = vscode.window.activeTextEditor;
if (editor) {
  vscode.window.showInformationMessage(`Editing: ${editor.document.fileName}`);
}

visibleTextEditors

Array of all visible text editors.

const editors = vscode.window.visibleTextEditors;
console.log(`${editors.length} editors visible`);

activeNotebookEditor

The currently focused notebook editor or undefined.

const notebook = vscode.window.activeNotebookEditor;
if (notebook) {
  console.log(`Notebook: ${notebook.notebook.uri.fsPath}`);
}

activeTerminal

The currently focused terminal or undefined.

const terminal = vscode.window.activeTerminal;
if (terminal) {
  terminal.sendText('echo Hello');
}

Editor Events

Monitor editor changes with these events:

// When active editor changes
vscode.window.onDidChangeActiveTextEditor(editor => {
  if (editor) {
    console.log('Switched to:', editor.document.fileName);
  }
});

// When visible editors change
vscode.window.onDidChangeVisibleTextEditors(editors => {
  console.log(`Now ${editors.length} visible editors`);
});

// When text selection changes
vscode.window.onDidChangeTextEditorSelection(event => {
  console.log('Selection changed in:', event.textEditor.document.fileName);
});

// When visible ranges change (scrolling)
vscode.window.onDidChangeTextEditorVisibleRanges(event => {
  console.log('Visible ranges changed');
});

Showing Documents

Open Text Documents

// Open and show a document
const uri = vscode.Uri.file('/path/to/file.ts');
const document = await vscode.workspace.openTextDocument(uri);

await vscode.window.showTextDocument(document, {
  viewColumn: vscode.ViewColumn.One,
  preserveFocus: false,
  preview: true
});

Open at Specific Location

await vscode.window.showTextDocument(document, {
  selection: new vscode.Range(10, 0, 10, 0), // Line 10
  viewColumn: vscode.ViewColumn.Beside
});

User Messages

Information Messages

vscode.window.showInformationMessage('Operation completed successfully!');

// With action buttons
const result = await vscode.window.showInformationMessage(
  'Do you want to continue?',
  'Yes',
  'No'
);

if (result === 'Yes') {
  // User clicked Yes
}

Warning and Error Messages

// Warning
vscode.window.showWarningMessage('This action cannot be undone');

// Error
vscode.window.showErrorMessage('Failed to save file', 'Retry', 'Cancel')
  .then(selection => {
    if (selection === 'Retry') {
      // Retry operation
    }
  });

const result = await vscode.window.showInformationMessage(
  'Important decision',
  { modal: true },
  'Confirm',
  'Cancel'
);

Quick Pick

Simple Quick Pick

const items = ['Option 1', 'Option 2', 'Option 3'];

const selected = await vscode.window.showQuickPick(items, {
  placeHolder: 'Select an option',
  canPickMany: false
});

if (selected) {
  vscode.window.showInformationMessage(`You picked: ${selected}`);
}

Quick Pick with Custom Items

interface MyQuickPickItem extends vscode.QuickPickItem {
  action: () => void;
}

const items: MyQuickPickItem[] = [
  {
    label: '$(file) New File',
    description: 'Create a new file',
    action: () => createNewFile()
  },
  {
    label: '$(folder) New Folder',
    description: 'Create a new folder',
    action: () => createNewFolder()
  }
];

const selected = await vscode.window.showQuickPick(items, {
  placeHolder: 'What do you want to create?'
});

if (selected) {
  selected.action();
}

Advanced Quick Pick

const quickPick = vscode.window.createQuickPick();
quickPick.items = [
  { label: 'Item 1' },
  { label: 'Item 2' },
  { label: 'Item 3' }
];
quickPick.placeholder = 'Select items';
quickPick.canSelectMany = true;

quickPick.onDidChangeSelection(selection => {
  console.log('Selected:', selection.map(s => s.label));
});

quickPick.onDidAccept(() => {
  const selected = quickPick.selectedItems;
  quickPick.hide();
  // Process selection
});

quickPick.show();

Input Box

Simple Input

const name = await vscode.window.showInputBox({
  prompt: 'Enter your name',
  placeHolder: 'John Doe',
  validateInput: (text) => {
    return text.length === 0 ? 'Name cannot be empty' : null;
  }
});

if (name) {
  vscode.window.showInformationMessage(`Hello, ${name}!`);
}

Password Input

const password = await vscode.window.showInputBox({
  prompt: 'Enter password',
  password: true,
  validateInput: (text) => {
    return text.length < 8 ? 'Password must be at least 8 characters' : null;
  }
});

Custom Input Box

const inputBox = vscode.window.createInputBox();
inputBox.prompt = 'Enter a value';
inputBox.placeholder = 'Type here...';

inputBox.onDidChangeValue(value => {
  // Validate as user types
  inputBox.validationMessage = value.length < 3 
    ? 'Must be at least 3 characters' 
    : undefined;
});

inputBox.onDidAccept(() => {
  const value = inputBox.value;
  inputBox.hide();
  // Process value
});

inputBox.show();

Terminals

Create Terminal

const terminal = vscode.window.createTerminal({
  name: 'My Terminal',
  cwd: '/path/to/directory'
});

terminal.show();
terminal.sendText('npm install');

Terminal Events

// When terminal opens
vscode.window.onDidOpenTerminal(terminal => {
  console.log('Terminal opened:', terminal.name);
});

// When terminal closes
vscode.window.onDidCloseTerminal(terminal => {
  console.log('Terminal closed:', terminal.name);
});

// When active terminal changes
vscode.window.onDidChangeActiveTerminal(terminal => {
  if (terminal) {
    console.log('Active terminal:', terminal.name);
  }
});

Access All Terminals

const terminals = vscode.window.terminals;
terminals.forEach(terminal => {
  console.log('Terminal:', terminal.name);
});

Output Channels

Create Output Channel

const outputChannel = vscode.window.createOutputChannel('My Extension');

outputChannel.appendLine('Extension activated');
outputChannel.appendLine('Performing operation...');

// Show the channel
outputChannel.show();

// Append without newline
outputChannel.append('Progress: ');
outputChannel.appendLine('100%');

// Clear
outputChannel.clear();

// Dispose when done
outputChannel.dispose();

Log Output Channel

const logChannel = vscode.window.createOutputChannel('My Extension', {
  log: true
});

logChannel.info('Information message');
logChannel.warn('Warning message');
logChannel.error('Error message');
logChannel.debug('Debug message');
logChannel.trace('Trace message');

Status Bar

Create Status Bar Item

const statusBarItem = vscode.window.createStatusBarItem(
  vscode.StatusBarAlignment.Left,
  100
);

statusBarItem.text = '$(sync~spin) Loading...';
statusBarItem.tooltip = 'Extension is loading';
statusBarItem.command = 'extension.command';
statusBarItem.show();

// Update later
setTimeout(() => {
  statusBarItem.text = '$(check) Ready';
  statusBarItem.tooltip = 'Extension is ready';
}, 2000);

// Hide and dispose
statusBarItem.hide();
statusBarItem.dispose();

Status Bar with Progress

const item = vscode.window.createStatusBarItem(vscode.StatusBarAlignment.Right);
item.text = '$(loading~spin) Processing';
item.show();

// Simulate work
await doWork();

item.text = '$(check) Complete';
setTimeout(() => item.dispose(), 2000);

Progress Indicators

Window Progress

vscode.window.withProgress({
  location: vscode.ProgressLocation.Window,
  title: 'Loading',
  cancellable: false
}, async (progress) => {
  progress.report({ increment: 0 });
  
  for (let i = 0; i < 100; i += 10) {
    await delay(100);
    progress.report({ 
      increment: 10, 
      message: `${i}% complete` 
    });
  }
});

Notification Progress

vscode.window.withProgress({
  location: vscode.ProgressLocation.Notification,
  title: 'Downloading files',
  cancellable: true
}, async (progress, token) => {
  token.onCancellationRequested(() => {
    console.log('User cancelled');
  });

  progress.report({ increment: 0, message: 'Starting...' });
  
  for (let i = 0; i < 100; i += 20) {
    if (token.isCancellationRequested) {
      break;
    }
    await delay(500);
    progress.report({ 
      increment: 20, 
      message: `Downloaded ${i}%` 
    });
  }
});

File Dialogs

Open File Dialog

const fileUri = await vscode.window.showOpenDialog({
  canSelectFiles: true,
  canSelectFolders: false,
  canSelectMany: false,
  filters: {
    'Text files': ['txt', 'md'],
    'All files': ['*']
  },
  title: 'Select a file'
});

if (fileUri && fileUri[0]) {
  console.log('Selected file:', fileUri[0].fsPath);
}

Save File Dialog

const uri = await vscode.window.showSaveDialog({
  defaultUri: vscode.Uri.file('/path/to/file.txt'),
  filters: {
    'Text files': ['txt'],
    'All files': ['*']
  },
  saveLabel: 'Save As'
});

if (uri) {
  await vscode.workspace.fs.writeFile(uri, Buffer.from('content'));
}

Select Folder Dialog

const folderUri = await vscode.window.showOpenDialog({
  canSelectFiles: false,
  canSelectFolders: true,
  canSelectMany: false,
  title: 'Select a folder'
});

Workspace Folder Picker

const folder = await vscode.window.showWorkspaceFolderPick({
  placeHolder: 'Select a workspace folder'
});

if (folder) {
  console.log('Selected folder:', folder.uri.fsPath);
}

Window State

Monitor Window State

// Current state
const state = vscode.window.state;
console.log('Window focused:', state.focused);

// Listen for changes
vscode.window.onDidChangeWindowState(state => {
  if (state.focused) {
    console.log('Window gained focus');
  } else {
    console.log('Window lost focus');
  }
});

Tab Groups

Access Tab Groups

const tabGroups = vscode.window.tabGroups;

// All tab groups
tabGroups.all.forEach(group => {
  console.log(`Group ${group.viewColumn}:`, group.tabs.length, 'tabs');
  
  group.tabs.forEach(tab => {
    if (tab.input instanceof vscode.TabInputText) {
      console.log('  -', tab.label, ':', tab.input.uri.fsPath);
    }
  });
});

// Active tab group
const activeGroup = tabGroups.activeTabGroup;
console.log('Active tab:', activeGroup.activeTab?.label);

Tab Group Events

vscode.window.tabGroups.onDidChangeTabs(event => {
  console.log('Opened tabs:', event.opened.map(t => t.label));
  console.log('Closed tabs:', event.closed.map(t => t.label));
  console.log('Changed tabs:', event.changed.map(t => t.label));
});

vscode.window.tabGroups.onDidChangeTabGroups(event => {
  console.log('Groups opened:', event.opened.length);
  console.log('Groups closed:', event.closed.length);
  console.log('Groups changed:', event.changed.length);
});

Best Practices

Use Appropriate Message Types

Choose the right message type for the situation. Reserve error messages for actual errors, not warnings or info.

// Good
vscode.window.showInformationMessage('File saved successfully');
vscode.window.showWarningMessage('File may contain syntax errors');
vscode.window.showErrorMessage('Failed to save file');

// Bad - using error for non-error situations
vscode.window.showErrorMessage('Operation completed');

Provide Context in Messages

Include relevant context in messages to help users understand what happened.

// Good
vscode.window.showErrorMessage(`Failed to load configuration from ${configPath}`);

// Bad - vague message
vscode.window.showErrorMessage('Something went wrong');

Use Progress Indicators for Long Operations

Show progress for any operation that takes more than a second.

await vscode.window.withProgress({
  location: vscode.ProgressLocation.Notification,
  title: 'Building project',
  cancellable: true
}, async (progress, token) => {
  // Long-running operation
});

Dispose UI Components

Always dispose of status bar items, output channels, and terminals when they’re no longer needed.

const statusItem = vscode.window.createStatusBarItem();
context.subscriptions.push(statusItem); // Auto-dispose on deactivation

// Or manually dispose
statusItem.dispose();

Validate User Input

Always validate input from showInputBox to ensure data quality.

const email = await vscode.window.showInputBox({
  prompt: 'Enter email address',
  validateInput: (text) => {
    const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
    return emailRegex.test(text) ? null : 'Invalid email address';
  }
});

Text Editor API

Work with text editors and documents

Workspace API

Access workspace files and folders

Commands API

Webview API

Create custom UI panels

Extension API

Core Services

Platform APIs

​Overview

​Active Editors

​Access Active Editor

​Editor Properties

​Editor Events

​Showing Documents

​Open Text Documents

​Open at Specific Location

​User Messages

​Information Messages

​Warning and Error Messages

​Modal Messages

​Quick Pick

​Simple Quick Pick

​Quick Pick with Custom Items

​Advanced Quick Pick

​Input Box

​Simple Input

​Password Input

​Custom Input Box

​Terminals

​Create Terminal

​Terminal Events

​Access All Terminals

​Output Channels

​Create Output Channel

​Log Output Channel

​Status Bar

​Create Status Bar Item

​Status Bar with Progress

​Progress Indicators

​Window Progress

​Notification Progress

​File Dialogs

​Open File Dialog

​Save File Dialog

​Select Folder Dialog

​Workspace Folder Picker

​Window State

​Monitor Window State

​Tab Groups

​Access Tab Groups

​Tab Group Events

​Best Practices

​Related APIs