节点 7.10 - 它支持等待吗？

Question

我在节点 7.10 上：

$ node --version
v7.10.0

我以为它支持await。

 let result = await Weather.findOne(options, function(err, weather) {

    if (err) {
        res.set('Content-Type', 'application/json');
        return res.status(200).send('Error occurs: ' + err);
    }

    if (weather) {
        res.set('Content-Type', 'application/json');
        return res.status(200).send(key + ' already exist.');
    }

    return weather;
});

console.log(result);

错误信息：

let result = await Weather.findOne(options, function(err, weather) {
                       ^^^^^^^
SyntaxError: Unexpected identifier
    at createScript (vm.js:53:10)
    at Object.runInThisContext (vm.js:95:10)
    at Module._compile (module.js:543:28)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:488:32)
    at tryModuleLoad (module.js:447:12)
    at Function.Module._load (module.js:439:3)
    at Module.require (module.js:498:17)
    at require (internal/module.js:20:19)
    at Object.<anonymous> (/var/www/html/projects/citizen-sense-dustbox-data-streams/es5/v4/app.js:33:15)
    at Module._compile (module.js:571:32)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:488:32)
    at tryModuleLoad (module.js:447:12)
    at Function.Module._load (module.js:439:3)
    at Module.require (module.js:498:17)
    at require (internal/module.js:20:19)
    at Object.<anonymous> (/var/www/html/projects/citizen-sense-dustbox-data-streams/es5/v4/bin/www:7:11)
    at Module._compile (module.js:571:32)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:488:32)
    at tryModuleLoad (module.js:447:12)
    at Function.Module._load (module.js:439:3)
    at Module.runMain (module.js:605:10)
    at run (bootstrap_node.js:427:7)
    at startup (bootstrap_node.js:151:9)
    at bootstrap_node.js:542:3

node 7.10 好像不支持？还是我做错了什么？

有什么想法吗？

Answer 1

来自https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/await：

The await operator is used to wait for a Promise. It can only be used inside an async function.

async function doAwait() {
    let result = await Weather.findOne(options, function(err, weather) {

       if (err) {
            res.set('Content-Type', 'application/json');
           return res.status(200).send('Error occurs: ' + err);
       }

       if (weather) {
           res.set('Content-Type', 'application/json');
           return res.status(200).send(key + ' already exist.');
       }

       return weather;
   });

   console.log(result);
}

Answer 2

我有 v7.10.0，await/async 绝对支持该版本。我认为它是在 7.4 中添加的，但不确定。

ubuntu@ubuntu:~$ node --version
v7.10.0

当我运行：

const getDate = async () => {
    return new Date()
}
const printDate = async () => {
    const date = await getDate()
    return date
}
printDate().then(console.log).catch(console.error)

我得到：

2017-07-04T09:04:27.311Z

编辑：仅供参考，async/await 实际上并没有进入 ES7。不过，它很可能会出现在今年的 ECMAScript 版本中。 https://github.com/tc39/proposals/blob/master/finished-proposals.md

节点 7.10 - 它支持等待吗？

node 7.10 - does it support await?

mongoose

node.js

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ecmascript-2017