顶层的 await

await 关键字可以用在 ECMAScript 模块的顶层主体中。

假设 a.mjs 具有

export const five = await Promise.resolve(5);

并且 b.mjs 具有

import { five } from './a.mjs';

console.log(five); // 记录 `5`

node b.mjs # 有效

如果顶层 await 表达式永远无法解析，则 node 进程将以 13 状态码退出。

import { spawn } from 'child_process';
import { execPath } from 'process';

spawn(execPath, [
  '--input-type=module',
  '--eval',
  // 永不解决的 Promise：
  'await new Promise(() => {})',
]).once('exit', (code) => {
  console.log(code); // 记录 `13`
});

The await keyword may be used in the top level body of an ECMAScript module.

Assuming an a.mjs with

export const five = await Promise.resolve(5);

And a b.mjs with

import { five } from './a.mjs';

console.log(five); // Logs `5`

node b.mjs # works

If a top level await expression never resolves, the node process will exit with a 13 status code.

import { spawn } from 'child_process';
import { execPath } from 'process';

spawn(execPath, [
  '--input-type=module',
  '--eval',
  // Never-resolving Promise:
  'await new Promise(() => {})',
]).once('exit', (code) => {
  console.log(code); // Logs `13`
});