typescript-language-server

What is typescript-language-server?

The typescript-language-server is an implementation of the Language Server Protocol (LSP) for TypeScript. It provides a range of features to enhance the development experience in editors and IDEs by offering functionalities like auto-completion, go-to-definition, and more.

Auto-completion

This code sets up a basic TypeScript Language Server that provides auto-completion suggestions. When the user types, the server can suggest completions like 'console.log'.

const { createConnection, TextDocuments } = require('vscode-languageserver');
const connection = createConnection();
const documents = new TextDocuments();

connection.onInitialize(() => {
  return {
    capabilities: {
      textDocumentSync: documents.syncKind,
      completionProvider: {
        resolveProvider: true
      }
    }
  };
});

connection.onCompletion(() => {
  return [
    {
      label: 'console.log',
      kind: 1,
      data: 1
    }
  ];
});

connection.listen();

Go-to-definition

This code sets up a TypeScript Language Server that provides go-to-definition functionality. When the user requests the definition of a symbol, the server responds with the location of the definition.

const { createConnection, TextDocuments } = require('vscode-languageserver');
const connection = createConnection();
const documents = new TextDocuments();

connection.onInitialize(() => {
  return {
    capabilities: {
      textDocumentSync: documents.syncKind,
      definitionProvider: true
    }
  };
});

connection.onDefinition((params) => {
  return {
    uri: params.textDocument.uri,
    range: {
      start: { line: 0, character: 0 },
      end: { line: 0, character: 10 }
    }
  };
});

connection.listen();

Diagnostics

This code sets up a TypeScript Language Server that provides diagnostics. It scans the document for 'TODO' comments and reports them as warnings.

const { createConnection, TextDocuments, Diagnostic, DiagnosticSeverity } = require('vscode-languageserver');
const connection = createConnection();
const documents = new TextDocuments();

connection.onInitialize(() => {
  return {
    capabilities: {
      textDocumentSync: documents.syncKind
    }
  };
});

documents.onDidChangeContent((change) => {
  const diagnostics = [];
  const text = change.document.getText();
  const pattern = /TODO/g;
  let match;
  while ((match = pattern.exec(text))) {
    diagnostics.push({
      severity: DiagnosticSeverity.Warning,
      range: {
        start: change.document.positionAt(match.index),
        end: change.document.positionAt(match.index + match[0].length)
      },
      message: `TODO found: ${match[0]}`,
      source: 'ex'
    });
  }
  connection.sendDiagnostics({ uri: change.document.uri, diagnostics });
});

connection.listen();

What is typescript-language-server?

What are typescript-language-server's main functionalities?

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