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Promises and async / await

Type asynchronous functions as Promise<T> and wait for them with await.

Runs in Zerethon IDE · TypeScript 7 Official TypeScript documentation ↗
main.ts 
const sleep = (ms: number): Promise<void> => new Promise((resolve) => setTimeout(resolve, ms));

async function job(name: string, ms: number): Promise<string> {
  await sleep(ms);
  return `${name} done`;
}

async function main(): Promise<void> {
  const results = await Promise.all([job('a', 30), job('b', 10)]);
  console.log(results);
  try {
    throw new Error('boom');
  } catch (err) {
    console.log('caught:', err instanceof Error ? err.message : err);
  }
}

main();

Output

[ 'a done', 'b done' ]
caught: boom

In strict mode a caught error has type unknown: check err instanceof Error before reading err.message.

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