Syntax Error: Unexpected Token async()

Question

I have been following this tutorial on using GraphQL and it has told me to write this block of code in my src/index.js file:

const express = require('express');
const bodyParser = require('body-parser');
const {graphqlExpress, graphiqlExpress} = require('apollo-server-express');
const schema = require('./schema');

// 1
const connectMongo = require('./mongo-connector');

// 2
const start = async () => {
  // 3
  const mongo = await connectMongo();
  var app = express();
  app.use('/graphql', bodyParser.json(), graphqlExpress({
    context: {mongo}, // 4
    schema
  }));
  app.use('/graphiql', graphiqlExpress({
    endpointURL: '/graphql',
  }));

  const PORT = 3000;
  app.listen(PORT, () => {
    console.log(`Hackernews GraphQL server running on port ${PORT}.`)
  });
};

// 5
start();

Though when I try to run the code using: node ./src/index.js it gives me this error:

const start = async () => {
                    ^

SyntaxError: Unexpected token (
    at createScript (vm.js:56:10)
    at Object.runInThisContext (vm.js:97:10)
    at Module._compile (module.js:542:28)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
    at Module.runMain (module.js:604:10)
    at run (bootstrap_node.js:389:7)
    at startup (bootstrap_node.js:149:9)

I've searched online and it seems that if might be caused by the node.js version from here but I've checked my noed.js version and it's 8.3.0 so it should be supported without having to use Babel if I'm not mistaken.

Here is my package.json file:

{
  "name": "graphql-js-tutorial",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "apollo-server-express": "^1.1.2",
    "body-parser": "^1.17.2",
    "express": "^4.15.4",
    "graphql": "^0.11.2",
    "graphql-tools": "^1.2.2",
    "mongodb": "^2.2.31"
  }
}

`async` is considered as a function name, and arrow functions don't accept names. — Teemu, Sep 04 '17 at 04:47
@JaromandaX In the context of `async` not recognized as a keyword, yes, I'm sure. — Teemu, Sep 04 '17 at 05:04
@Teemu - that code works fine in nodejs 8.4 (available since node 8.3) — Jaromanda X, Sep 04 '17 at 05:04
there's your issue ... seeing as you aren't even using `async` correctly if it were supported, just don't use it — Jaromanda X, Sep 04 '17 at 05:05
@JaromandaX Yes, it does, but OP apparently doesn't use the said version. Only I've said, that the error is fired because of the named arrow function, and that still stands. — Teemu, Sep 04 '17 at 05:07
Though when I type `brew upgrade node` it says I can't upgrade as I'm on version `8.3.0` — YellowPillow, Sep 04 '17 at 05:08
well, if you actually were on 8.3 you wouldn't see this problem - I think you probably have multiple versions of node installed — Jaromanda X, Sep 04 '17 at 05:12
@Teemu - I do understand now - I did assume from the syntax that the intent was to use (badly) `async` function - which does seem to be the case — Jaromanda X, Sep 04 '17 at 05:14
@YellowPillow don't use Homebrew to install Node.js, it gives nothing but grief. Use the official installer. — robertklep, Sep 04 '17 at 06:55

Jaromanda X · Answer 1 · 2017-09-04T05:20:04.370

5

async functions are only available since node 8.3

your code is equivalent to (without async/await)

const start = () => {
    return connectMongo().then(mongo => {
        var app = express();
        app.use('/graphql', bodyParser.json(), graphqlExpress({
            context: {mongo}, // 4
            schema
        }));
        app.use('/graphiql', graphiqlExpress({
            endpointURL: '/graphql',
        }));

        const PORT = 3000;
        app.listen(PORT, () => {
            console.log(`Hackernews GraphQL server running on port ${PORT}.`)
        });
        return;
    });
};

edited Sep 04 '17 at 05:20

answered Sep 04 '17 at 05:09

Jaromanda X

53,868
5
73
87

This happened to me today when I was trying to run code in Node 6.x that was intended for 8.x where async functions are now fully supported. – rainabba Apr 13 '18 at 18:20

score -1 · Answer 2 · answered Sep 04 '17 at 08:14

-1

start your app by the command node yourAppFile -harmony! async function is available in the harmony mode under Node7.+

answered Sep 04 '17 at 08:14

lx1412

1,160
6
14

How does that help the OP - running `6.11.2` (which wont enable async) or if he's running `8.3` like `brew` is telling him, he doesn't need the flag – Jaromanda X Sep 04 '17 at 09:02

Syntax Error: Unexpected Token async()

2 Answers2