Question

我在blog of version 14.3 release中读到，该版本支持“顶级等待”。这是否意味着该代码必须有效，如果没有，[支持顶层等待]的含义是什么

let x = 0

let myFunc = () => {
    setTimeout(() => {
    x = 2
    }, 1000)
  return x
  }

let y = await myFunc()

console.log(y)

因为它在我更新的节点环境中不起作用

Answer 1

是的，确实，Node.js现在已经支持顶级等待，尽管该语言尚未完全实现stage 3。您可以使用x <- read.table(header=TRUE, text=" Sex Height 1 Male 75 2 Male 70 3 Male 68 4 Male 74 5 Male 61 6 Female 65")标志

运行Node.js脚本。

--harmony-top-level-await

node --harmony-top-level-await ./beer.js

您可能仍然会收到以下错误；

async function beer(){
    return "?"
}

const result = await test();
console.log(result); // "?"

要解决此问题，您需要告诉节点您的脚本属于模块类型。您可以通过以下两种方法来实现；

将package.json SyntaxError: await is only valid in an async function设置为type

module

{
  "main": "beer.js",
  "type": "module"
}

或更改为node --harmony-top-level-await ./beer.js扩展名.mjs

./beer.js => ./beer.mjs

Answer 2

是的，正如@DanStarns在回答中所说的那样，

我尝试实现此示例，

import axios from 'axios';

const response = await axios('https://quote-garden.herokuapp.com/api/v2/quotes/random');
console.log(response.data);

package.json

{
  "name": "async-await-top",
  "version": "1.0.0",
  "description": "",
  "main": "top-level-async-await.js",
  "type": "module",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "axios": "^0.19.2"
  }
}

带有标志运行

node --harmony-top-level-await top-level-async-await.js

输出

G:\async-await-top>node --harmony-top-level-await top-level-async-await.js
{
  statusCode: 200,
  quote: {
    _id: '5eb17aaeb69dc744b4e72b82',
    quoteText: 'I can take more punishment than anyone in the business.',
    quoteAuthor: 'Ric Flair',
    quoteGenre: 'business',
    __v: 0
  }
}

在节点-v 14.3中等待异步功能外

2 个答案: