异步箭头功能的语法错误

Question

I am following this example, but on this section of code...

const getApiAndEmit = async socket => {
  try {
    const res = await axios.get(
      "https://api.darksky.net/forecast/PUT_YOUR_API_KEY_HERE/43.7695,11.2558"
    ); // Getting the data from DarkSky
    socket.emit("FromAPI", res.data.currently.temperature); // Emitting a new message. It will be consumed by the client
  } catch (error) {
    console.error(`Error: ${error.code}`);
  }
};

I get the following error

D:\Documents\js\socketio-server\app.js:42
const getApiAndEmit = async socket => {
                        ^^^^^^
SyntaxError: Unexpected identifier
    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)
PS D:\Documents\js\socketio-server>

Answer 1

The function syntax seems correct. You may need to update node, as async support didn't arrive until early this year (edit: version 7.6 after googling).

You can rewrite using promises or try the --harmony flag when running from the command line.

Answer 2

You need to upgrade to node 7.6 (or higher ) since the async keyword wasn't supported in earlier versions. As of right now, 6.11 is the LST version and 8.3 is the latest.

Answer 3

should enclose function with parentheses ()

const getApiAndEmit = async (socket => {
  try {
    const res = await axios.get(
      "https://api.darksky.net/forecast/PUT_YOUR_API_KEY_HERE/43.7695,11.2558"
    ); // Getting the data from DarkSky
    socket.emit("FromAPI", res.data.currently.temperature); // Emitting a new message. It will be consumed by the client
  } catch (error) {
    console.error(`Error: ${error.code}`);
  }
});