Text Editor API

The Text Editor API provides functionality to interact with text editors, manipulate text documents, apply edits, and control editor appearance and behavior.

Core Interfaces

TextEditor

Represents an editor attached to a document. Access the active editor via window.activeTextEditor.

interface TextEditor {
    readonly document: TextDocument;
    selection: Selection;
    selections: readonly Selection[];
    readonly visibleRanges: readonly Range[];
    options: TextEditorOptions;
    readonly viewColumn: ViewColumn | undefined;
    
    edit(callback: (editBuilder: TextEditorEdit) => void): Thenable<boolean>;
    insertSnippet(snippet: SnippetString, location?: Position | Range): Thenable<boolean>;
    setDecorations(decorationType: TextEditorDecorationType, ranges: Range[]): void;
    revealRange(range: Range, revealType?: TextEditorRevealType): void;
}

document

TextDocument

The document associated with this editor

selection

Selection

The primary selection (always at index 0)

selections

readonly Selection[]

All selections in this editor

visibleRanges

readonly Range[]

Currently visible ranges (accounts for vertical scrolling only)

TextDocument

Represents a text document such as a source file.

interface TextDocument {
    readonly uri: Uri;
    readonly fileName: string;
    readonly isUntitled: boolean;
    readonly languageId: string;
    readonly version: number;
    readonly isDirty: boolean;
    readonly isClosed: boolean;
    readonly eol: EndOfLine;
    readonly lineCount: number;
    
    save(): Thenable<boolean>;
    lineAt(line: number | Position): TextLine;
    offsetAt(position: Position): number;
    positionAt(offset: number): Position;
    getText(range?: Range): string;
    getWordRangeAtPosition(position: Position, regex?: RegExp): Range | undefined;
    validateRange(range: Range): Range;
    validatePosition(position: Position): Position;
}

Working with Editors

Accessing the Active Editor

import * as vscode from 'vscode';

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);
}

Listening to Editor Changes

vscode.window.onDidChangeActiveTextEditor(editor => {
    if (editor) {
        console.log('Active editor changed to:', editor.document.fileName);
    } else {
        console.log('No active editor');
    }
});

Making Text Edits

Using TextEditorEdit

The edit method provides an edit builder for making changes:

const editor = vscode.window.activeTextEditor;
if (editor) {
    editor.edit(editBuilder => {
        const selection = editor.selection;
        
        // Replace selected text
        editBuilder.replace(selection, 'New text');
        
        // Insert at cursor
        editBuilder.insert(selection.start, 'Prefix: ');
        
        // Delete a range
        const lineRange = editor.document.lineAt(0).range;
        editBuilder.delete(lineRange);
        
        // Set end of line
        editBuilder.setEndOfLine(vscode.EndOfLine.LF);
    }).then(success => {
        console.log('Edit applied:', success);
    });
}

Changes in the edit builder are applied atomically when the callback completes. The builder is only valid during callback execution.

Edit Options

Control undo/redo behavior:

editor.edit(editBuilder => {
    editBuilder.replace(range, text);
}, {
    undoStopBefore: false,  // Don't create undo stop before
    undoStopAfter: true     // Create undo stop after
});

Multiple Cursor Editing

editor.edit(editBuilder => {
    // Apply edits to all selections
    for (const selection of editor.selections) {
        const text = editor.document.getText(selection);
        editBuilder.replace(selection, text.toUpperCase());
    }
});

Working with Positions and Ranges

Position Class

// Create a position (line 10, character 5)
const pos = new vscode.Position(10, 5);

// Compare positions
if (pos1.isBefore(pos2)) {
    console.log('pos1 comes before pos2');
}

// Translate position
const newPos = pos.translate(1, 0);  // Move down one line
const relative = pos.translate({ lineDelta: -2, characterDelta: 3 });

// Create new position
const adjusted = pos.with(5, 10);  // Line 5, character 10
const sameLine = pos.with(undefined, 0);  // Same line, character 0

line

number

required

Zero-based line number

character

number

required

Zero-based character offset (UTF-16 code units)

Range Class

// Create a range
const range = new vscode.Range(0, 0, 5, 10);
// Or from positions
const range2 = new vscode.Range(
    new vscode.Position(0, 0),
    new vscode.Position(5, 10)
);

// Range properties
console.log(range.isEmpty);       // true if start === end
console.log(range.isSingleLine);  // true if start.line === end.line

// Check containment
if (range.contains(position)) {
    console.log('Position is in range');
}

// Range operations
const intersection = range1.intersection(range2);
const union = range1.union(range2);

Selection Class

// Selection extends Range with anchor and active
const selection = new vscode.Selection(10, 5, 15, 20);

console.log(selection.anchor);     // Position where selection started
console.log(selection.active);     // Current cursor position
console.log(selection.isReversed); // true if anchor > active

// Set selection
editor.selection = new vscode.Selection(5, 0, 5, 10);

// Multiple selections
editor.selections = [
    new vscode.Selection(0, 0, 0, 5),
    new vscode.Selection(1, 0, 1, 5),
    new vscode.Selection(2, 0, 2, 5)
];

Working with Documents

Reading Document Content

const document = editor.document;

// Get all text
const fullText = document.getText();

// Get text in range
const range = new vscode.Range(0, 0, 5, 0);
const text = document.getText(range);

// Get line
const line = document.lineAt(10);
console.log(line.text);
console.log(line.firstNonWhitespaceCharacterIndex);

// Get word at position
const wordRange = document.getWordRangeAtPosition(position);
if (wordRange) {
    const word = document.getText(wordRange);
}

Document Events

Document Changes
Document Open/Close
Document Save

vscode.workspace.onDidChangeTextDocument(event => {
    const document = event.document;
    const changes = event.contentChanges;
    const reason = event.reason; // Undo/Redo/Revert
    
    console.log(`Document changed: ${document.fileName}`);
    for (const change of changes) {
        console.log(`Range: ${change.range}, Text: ${change.text}`);
    }
});

// Document opened
vscode.workspace.onDidOpenTextDocument(document => {
    console.log('Opened:', document.fileName);
});

// Document closed
vscode.workspace.onDidCloseTextDocument(document => {
    console.log('Closed:', document.fileName);
});

// Before save
vscode.workspace.onWillSaveTextDocument(event => {
    const document = event.document;
    const reason = event.reason;
    
    // Provide edits to apply before save
    event.waitUntil(
        Promise.resolve([/* text edits */])
    );
});

// After save
vscode.workspace.onDidSaveTextDocument(document => {
    console.log('Saved:', document.fileName);
});

Text Decorations

Creating Decoration Types

const decorationType = vscode.window.createTextEditorDecorationType({
    backgroundColor: 'rgba(255, 0, 0, 0.3)',
    border: '1px solid red',
    borderRadius: '3px',
    cursor: 'pointer',
    after: {
        contentText: ' // Note',
        color: 'gray',
        fontStyle: 'italic'
    },
    isWholeLine: false,
    overviewRulerColor: 'red',
    overviewRulerLane: vscode.OverviewRulerLane.Right
});

context.subscriptions.push(decorationType);

Applying Decorations

// Apply decorations to ranges
const ranges = [
    new vscode.Range(0, 0, 0, 5),
    new vscode.Range(1, 0, 1, 5)
];

editor.setDecorations(decorationType, ranges);

// With hover messages
const options: vscode.DecorationOptions[] = ranges.map(range => ({
    range,
    hoverMessage: new vscode.MarkdownString('**Hover text**')
}));

editor.setDecorations(decorationType, options);

// Clear decorations
editor.setDecorations(decorationType, []);

Inserting Snippets

SnippetString

const snippet = new vscode.SnippetString();

// Add tabstops
snippet.appendText('function ');
snippet.appendPlaceholder('name');
snippet.appendText('(');
snippet.appendPlaceholder('params');
snippet.appendText(') {\n\t');
snippet.appendTabstop(0);  // Final cursor position
snippet.appendText('\n}');

// Insert snippet
editor.insertSnippet(snippet);

Variable Snippets

const snippet = new vscode.SnippetString();

// Use variables
snippet.appendText('File: ');
snippet.appendVariable('TM_FILENAME', 'untitled');
snippet.appendText('\n');
snippet.appendText('Date: ');
snippet.appendVariable('CURRENT_DATE', new Date().toISOString());

editor.insertSnippet(snippet);

Revealing Ranges

// Reveal a range in the editor
const range = new vscode.Range(100, 0, 100, 10);

// Default - minimal scrolling
editor.revealRange(range);

// Center in viewport
editor.revealRange(range, vscode.TextEditorRevealType.InCenter);

// At top of viewport
editor.revealRange(range, vscode.TextEditorRevealType.AtTop);

// Center if outside viewport
editor.revealRange(
    range,
    vscode.TextEditorRevealType.InCenterIfOutsideViewport
);

Editor Options

// Get current options
const options = editor.options;
console.log('Tab size:', options.tabSize);
console.log('Insert spaces:', options.insertSpaces);

// Set options
editor.options = {
    tabSize: 4,
    insertSpaces: true,
    cursorStyle: vscode.TextEditorCursorStyle.Line,
    lineNumbers: vscode.TextEditorLineNumbersStyle.On
};

tabSize

number | string

Size of a tab in spaces (or “auto”)

insertSpaces

boolean | string

Insert spaces when pressing Tab (or “auto”)

cursorStyle

TextEditorCursorStyle

Rendering style of the cursor

lineNumbers

TextEditorLineNumbersStyle

Line number display style

Common Patterns

Transform Selected Text

vscode.commands.registerTextEditorCommand(
    'extension.uppercase',
    (editor, edit) => {
        for (const selection of editor.selections) {
            const text = editor.document.getText(selection);
            edit.replace(selection, text.toUpperCase());
        }
    }
);

Insert Text at Cursor

const editor = vscode.window.activeTextEditor;
if (editor) {
    const position = editor.selection.active;
    editor.edit(editBuilder => {
        editBuilder.insert(position, 'Inserted text');
    });
}

Replace Text in Document

const document = editor.document;
const fullRange = new vscode.Range(
    document.positionAt(0),
    document.positionAt(document.getText().length)
);

editor.edit(editBuilder => {
    editBuilder.replace(fullRange, newText);
});

Best Practices

Performance

Batch multiple edits in a single edit() call
Use getText() with ranges instead of getting all text
Dispose decoration types when no longer needed
Cache document references when processing multiple times

User Experience

Respect user’s tab/space settings
Preserve selections when possible
Use appropriate undo stops for complex operations
Provide feedback for long-running operations

Correctness

Always validate positions and ranges
Handle case when no active editor exists
Account for multi-cursor scenarios
Use UTF-16 code units for character offsets

Commands API - Register text editor commands
Workspace API - Open and manage documents
Languages API - Provide language features

Extension API

Core Services

Platform APIs

Text Editor API

Text Editor API

Core Interfaces

TextEditor

TextDocument

Working with Editors

Accessing the Active Editor

Listening to Editor Changes

Making Text Edits

Using TextEditorEdit

Edit Options

Multiple Cursor Editing

Working with Positions and Ranges

Position Class

Range Class

Selection Class

Working with Documents

Reading Document Content

Document Events

Text Decorations

Creating Decoration Types

Applying Decorations

Inserting Snippets

SnippetString

Variable Snippets

Revealing Ranges

Editor Options

Common Patterns

Transform Selected Text

Insert Text at Cursor

Replace Text in Document

Best Practices

Extension API

Core Services

Platform APIs

​Text Editor API

​Core Interfaces

​TextEditor

​TextDocument

​Working with Editors

​Accessing the Active Editor

​Listening to Editor Changes

​Making Text Edits

​Using TextEditorEdit

​Edit Options

​Multiple Cursor Editing

​Working with Positions and Ranges

​Position Class

​Range Class

​Selection Class

​Working with Documents

​Reading Document Content

​Document Events

​Text Decorations

​Creating Decoration Types

​Applying Decorations

​Inserting Snippets

​SnippetString

​Variable Snippets

​Revealing Ranges

​Editor Options

​Common Patterns

​Transform Selected Text

​Insert Text at Cursor

​Replace Text in Document

​Best Practices

​Related APIs

Text Editor API

Core Interfaces

TextEditor

TextDocument

Working with Editors

Accessing the Active Editor

Listening to Editor Changes

Making Text Edits

Using TextEditorEdit

Edit Options

Multiple Cursor Editing

Working with Positions and Ranges

Position Class

Range Class

Selection Class

Working with Documents

Reading Document Content

Document Events

Text Decorations

Creating Decoration Types

Applying Decorations

Inserting Snippets

SnippetString

Variable Snippets

Revealing Ranges

Editor Options

Common Patterns

Transform Selected Text

Insert Text at Cursor

Replace Text in Document

Best Practices

Related APIs