SyntaxError: Unexpected token function - Async Await Nodejs

问题:

I was experimenting on using Node version 6.2.1 with some of my code. Had plans to migrate most of the hyper-callback oriented codes to something that looks cleaner and maybe performs better.

I have no clue why, the terminal throws up an error when I try to execute the node code.

helloz.js

(async function testingAsyncAwait() {     await console.log("For Trump's Sake Print me!"); })(); 

Logs-

BOZZMOB-M-T0HZ:rest bozzmob$ node helloz.js  /Users/bozzmob/Documents/work/nextgennms/rest/helloz.js:1 (function (exports, require, module, __filename, __dirname) { (async function testingAsyncAwait() {                                                                      ^^^^^^^^ SyntaxError: Unexpected token function     at Object.exports.runInThisContext (vm.js:53:16)     at Module._compile (module.js:513:28)     at Object.Module._extensions..js (module.js:550:10)     at Module.load (module.js:458:32)     at tryModuleLoad (module.js:417:12)     at Function.Module._load (module.js:409:3)     at Function.Module.runMain (module.js:575:10)     at startup (node.js:160:18)     at node.js:456:3 BOZZMOB-M-T0HZ:rest bozzmob$ node -v v6.2.1 

What am I missing? Please throw me some light on the same.

---

Update 1:

I tried to use Babel as Quentin suggested, But, I am getting the following error still.

Updated Code-

require("babel-core/register"); require("babel-polyfill");

(async function testingAsyncAwait() {     await console.log("For Trump's Sake Print me!"); })(); 

Logs-

BOZZMOB-M-T0HZ:rest bozzmob$ babel helloz.js > helloz.trans.js SyntaxError: helloz.js: Unexpected token (3:7)   1 | require("babel-polyfill");   2 |  > 3 | (async function testingAsyncAwait() {     |        ^   4 |     await console.log("For Trump's Sake Print me!");   5 | })(); 

回答1:

Async functions are not supported by Node versions older than version 7.6.

You'll need to transpile your code (e.g. using Babel) to a version of JS that Node understands if you are using an older version.

回答2:

Nodejs supports async/await from version 7.6.

Release post: https://v8project.blogspot.com.br/2016/10/v8-release-55.html

回答3:

Node.JS does not fully support ES6 currently, so you can either use asyncawait module or transpile it using Bable.

install

npm install --save asyncawait 

helloz.js

var async = require('asyncawait/async'); var await = require('asyncawait/await');  (async (function testingAsyncAwait() {     await (console.log("For Trump's Sake Print me!")); }))(); 

回答4:

If you are just experimenting you can use babel-node command line tool to try out the new JavaScript features

1. Install babel-cli into your project

   $ npm install --save-dev babel-cli

2. Install the presets

   $ npm install --save-dev babel-preset-es2015 babel-preset-es2017

3. Setup your babel presets

   Create .babelrc in the project root folder with the following contents:

   { "presets": ["es2015","es2017"] }

4. Run your script with babel-node

   $ babel-node helloz.js

This is only for development and testing but that seems to be what you are doing. In the end you'll want to set up webpack (or something similar) to transpile all your code for production

• babel-node sample code : https://github.com/stujo/javascript-async-await/tree/15abac

If you want to run the code somewhere else, webpack can help and here is the simplest configuration I could work out:

• Full webpack example : https://github.com/stujo/javascript-async-await

回答5:

node v6.6.0

If you just use in development. You can do this:

npm i babel-cli babel-plugin-transform-async-to-generator babel-polyfill --save-dev

the package.json would be like this:

"devDependencies": { "babel-cli": "^6.18.0", "babel-plugin-transform-async-to-generator": "^6.16.0", "babel-polyfill": "^6.20.0" }

create .babelrc file and write this:

{ "plugins": ["transform-async-to-generator"] }

and then, run your async/await script like this:

./node_modules/.bin/babel-node script.js

文章来源: SyntaxError: Unexpected token function - Async Await Nodejs