节点：尝试使用`async function`抛出错误

Question

I only have:

router.post('/register', async (req, res) => {
    // planning to use await in here
});    

But I'm getting this error. I have tried googling if node supports await/async but I cannot seem to get any headway, I just keep finding native modules to implement it into node (Which could very well be the issue, but I'm really hoping its a syntax error and that node supports async/await natively)

router.post('/register', async (req, res) => {
                           ^

SyntaxError: Unexpected token (
at exports.runInThisContext (vm.js:53:16)
at Module._compile (module.js:374:25)
at Object.Module._extensions..js (module.js:405:10)
at Module.load (module.js:344:32)
at Function.Module._load (module.js:301:12)
at Module.require (module.js:354:17)
at require (internal/module.js:12:17)
at Object.<anonymous> (/app.js:13:15)
at Module._compile (module.js:398:26)
at Object.Module._extensions..js (module.js:405:10)
at Module.load (module.js:344:32)
at Function.Module._load (module.js:301:12)
at Module.require (module.js:354:17)
at require (internal/module.js:12:17)
at Object.<anonymous> (/www:7:11)
at Module._compile (module.js:398:26)

Any information would be great thanks.

Answer 1

One option you have here is babel , which will can transpile ES7 syntax like this into something node can run. Since ES7 is still a work in progress you don't get async/await out of the box, but babel offers a transform ( https://babeljs.io/docs/plugins/transform-async-to-generator/ ) that you can include to make this work.

Edit: babel has this included in their stage3 preset. So once you npm install babel and the preset:

npm install babel-core babel-preset-stage-3

And install babel-cli globally so you can run babel-node in your shell

npm install -g babel-cli

Create a .babelrc like this:

{
  "presets": [
    "stage-3"
  ]
}

And a test script like this:

'use strict';

function bar() {
    return Promise.resolve('banana');
}

async function foo() {
    return await bar();
}

foo().then(console.log);

You can confirm it's working like so:

▶ babel-node test.js
banana