TypeScript5.2引入新关键字using介绍

{
  const getResource = () => {
    return {
      [Symbol.dispose]: () => {
        console.log('Hooray!')
      }
    }
  }
  using resource = getResource();
} // 'Hooray!' logged to console

const resource = {
  [Symbol.dispose]: () => {
    console.log("Hooray!");
  },
};

const getResource = () => ({
  [Symbol.asyncDispose]: async () => {
    await someAsyncFunc();
  },
});
{
  await using resource = getResource();
}

import { open } from "node:fs/promises";
let filehandle;
try {
  filehandle = await open("thefile.txt", "r");
} finally {
  await filehandle?.close();
}

import { open } from "node:fs/promises";
const getFileHandle = async (path: string) => {
  const filehandle = await open(path, "r");
  return {
    filehandle,
    [Symbol.asyncDispose]: async () => {
      await filehandle.close();
    },
  };
};
{
  await using file = getFileHandle("thefile.txt");
  // Do stuff with file.filehandle
} // Automatically disposed!

const connection = await getDb();
try {
  // Do stuff with connection
} finally {
  await connection.close();
}

const getConnection = async () => {
  const connection = await getDb();
  return {
    connection,
    [Symbol.asyncDispose]: async () => {
      await connection.close();
    },
  };
};
{
  await using { connection } = getConnection();
  // Do stuff with connection
} // Automatically closed!