Snippet

Explicit Async Resource Management using Symbol.asyncDispose

This expert snippet illustrates the Stage 3 Explicit Resource Management feature in TypeScript using `Symbol.asyncDispose` and `await using`. It guarantees reliable asynchronous resource teardown when execution leaves scope, eliminating manual `try...finally` cleanup blocks.

snippet.ts

typescript

class DatabaseConnection implements AsyncDisposable {
  private active = true;
 
  public async query(sql: string): Promise<unknown[]> {
    if (!this.active) throw new Error('Connection closed');
    return [{ id: 1, query: sql }];
  }
 
  async [Symbol.asyncDispose](): Promise<void> {
    if (this.active) {
      this.active = false;
      await new Promise((resolve) => setTimeout(resolve, 10));
    }
  }
}
 
async function executeTransaction(): Promise<void> {
  await using conn = new DatabaseConnection();
  await conn.query('SELECT * FROM users');
}

Breakdown

class DatabaseConnection implements AsyncDisposable

Implements the global standard AsyncDisposable interface for resource cleanup compliance.

async [Symbol.asyncDispose](): Promise<void>

Defines the asynchronous tear-down logic executed automatically upon scope exit.

await using conn = new DatabaseConnection();

Uses the resource declaration syntax to bind lifecycle cleanup to the block scope.

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Explicit Async Resource Management using Symbol.asyncDispose

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