why can't I use async / await

[npomfret]

If I try to use syntax like async (req, res) => {... in my firebase function I get the error below when deploying. I assume it's a language feature that's not supported yet?

error Parsing error: Unexpected token =>

Removing the async makes it go away...

However, I have a dependency in my package (ccxt) that does use the async / await syntax, and it works just fine. Why is this?

[nathanjliu]

async/await is only supported in the Node 8 runtime, which was only recently added as a beta runtime in firebase functions.

You can use it by adding the following to your package.json.
"engines": { "node": "8" },

[andrewspy]

I have similar issue with the following typescript code, targeting es2017 and Node 8 runtime.

index.ts:-

import * as admin from 'firebase-admin';
import * as functions from 'firebase-functions';

admin.initializeApp();

export const someFunctionA = functions.database.ref('/sample')
  .onWrite(async (change, context) => {
    console.log(change, context);
    
    return 0;
  }
);

tsconfig.json:-

{
  "compilerOptions": {
    "lib": ["es2017"],
    "module": "commonjs",
    "noImplicitReturns": true,
    "outDir": "lib",
    "sourceMap": true,
    "target": "es2017"
  },
  "compileOnSave": true,
  "include": [
    "src"
  ]
}

package.json-

{
  "name": "functions",
  "scripts": {
    "lint": "tslint --project tsconfig.json",
    "build": "tsc",
    "serve": "npm run build && firebase serve --only functions",
    "shell": "npm run build && firebase functions:shell",
    "start": "npm run shell",
    "deploy": "firebase deploy --only functions",
    "logs": "firebase functions:log"
  },
  "engines": {
    "node": "8"
  },
  "main": "lib/index.js",
  "dependencies": {
    "firebase-admin": "~6.0.0",
    "firebase-functions": "^2.0.3"
  },
  "devDependencies": {
    "tslint": "~5.8.0",
    "typescript": "~2.8.3"
  },
  "private": true
}

Actual Result

!  functions[someFunctionA]: Deployment error.
Function load error: Code in file lib/index.js can't be loaded.
Is there a syntax error in your code?
Detailed stack trace: /user_code/lib/index.js:7
    .onWrite(async (change, context) => {
                   ^

SyntaxError: Unexpected token (
    at createScript (vm.js:56:10)
    at Object.runInThisContext (vm.js:97:10)
    at Module._compile (module.js:549:28)
    at Object.Module._extensions..js (module.js:586:10)
    at Module.load (module.js:494:32)
    at tryModuleLoad (module.js:453:12)
    at Function.Module._load (module.js:445:3)
    at Module.require (module.js:504:17)
    at require (internal/module.js:20:19)
    at getUserFunction (/var/tmp/worker/worker.js:391:24)

[andrewspy]

Just noticed that my firebase-tools was not updated to v4.0. Everything works fine now after updating firebase-tools to latest version.

[thechenky]

@npomfret closing this out as it seems like others have resolved this issue, but feel free to open another bug if you're still having problems.

[stamler]

If anybody else is continuing to receive this issue after doing the updates, make sure that "ecmaVersion": 8 is set in your .eslintrc.json as well.

[kiralikbeyin]

If anybody else is continuing to receive this issue after doing everything, make sure that you are using node v8 in your computer :)

nvm ls

[bashizip]

This should be well documented in the official doc !!

[justinh00k]

Yep, fixed it for me and never would have found it on my own!

[bashizip]

Firebase functions just don't work!,

[kireerik]

@thechenky I think we should open this issue, because #319 (comment) is only a workaround.

[viveky259259]

Update ecmaVersion to 8 like this in file .eslintrc.js

module.exports = {
root: true,
env: {
es6: true,
node: true,
},
parserOptions: {
"ecmaVersion": 8,
"sourceType": "module"
},
extends: [
"eslint:recommended",
"google",
],
rules: {
quotes: ["error", "double"],
},
};

[aatmansp]

There is a typo in function's package.json.
Given:
"scripts": {
"lint": "eslint .",
...
}

But it should be:
"scripts": {
"lint": "eslint",
...
}

Note: "..." represents other scripts.