Using async/await in node 7.4

问题

I thought async/await was supported in node 7.4, however this example does not work:

const Promise = require('bluebird');

async function main(){
  await Promise.delay(1000)
}

main();

Results in:

async function main(){
      ^^^^^^^^
SyntaxError: Unexpected token function

How can I use async/await with node 7.4?

回答1:

Yes async-await is supported in Node.js v7 but its locked behind the harmony flag. Features which are not yet production ready are behind this flag.

To use async-await in Node.js v7 simply run Node service with this flag -

node --harmony-async-await app.js

The official release of async-await is slated for Node.js v8 which will be launched in April.

You can follow this pull request to check its status. Basically the correct functioning of async-await is dependent on the integration of V8 engine v5.5 into Node.js. Currently Node.js uses V8 v5.4 which is solved by this pull request.

Update 1 - It seems V8 v5.5 might be coming to Node.js v7. Follow this pull request for more details.

Update 2 - Good news guys! Node.js version 7.6.0 now officially supports async functions without using the --harmony flag as V8 engine 5.5 has been successfully ported.

Now you only need to use the --harmony flag if your Node.js version is between 7.0 to 7.5.0 (inclusive). For complete changelog refer here.

回答2:

Node.js 7.6.0 released several hours ago and they included v8 5.5. Now you can use async/await without flag.

回答3:

You will need harmony flag for this to work.

Try again with node --harmony-async-await myscript.js

回答4:

Node version 7.6 now supports async/await out of the box. If you haven’t tried it yet, you should adopt it immediately and never look back.

  const makeRequest = () =>
      getJSON()
        .then(data => {
          console.log(data)
          return "done"
        })

    makeRequest()

And using async/await:

const makeRequest = async () => {
  console.log(await getJSON())
  return "done"
}

makeRequest()

回答5:

I had the same issue, what I did is installed asyncawait using below command

npm install asyncawait

afterwards i declared await and async using below command

const async = require('asyncawait/async');
const await = require('asyncawait/await');

then used these where it was required but my commands were within async(my-code) & await(my-code).

And it worked perfectly for me.

来源：https://stackoverflow.com/questions/41756622/using-async-await-in-node-7-4

标签

node.js

async-await