async function with the class in javascript

Question

I have create a class in nodejs

class ApnService {
  sendNotification(deviceType, deviceToken, msg, type, id) {
    try {
      const note = await apnProvider.send(note, deviceToken)
      console.log(note)
    } catch (err) {
      console.log(err)
    }
  }
}

export default ApnService

What I need to do is to convert above function to async. But when I use below syntax It throws me error

SyntaxError: src/services/apn.js: Unexpected token (43:19)
  41 |   }
  42 | 
> 43 |   sendNotification = async(deviceType, deviceToken, msg, type, id) => {
     | 

               ^

Below is the syntax

class ApnService {
  sendNotification = async(deviceType, deviceToken, msg, type, id) => {
    try {
      const note = await apnProvider.send(note, deviceToken)
      console.log(note)
    } catch (err) {
      console.log(err)
    }
  }
}

export default ApnService

Aniket Pawar · Accepted Answer · 2018-11-15 06:22:20Z

23

You can simply add async before function name to declare that function as async,

class ApnService {
  async sendNotification(deviceType, deviceToken, msg, type, id) {
    try {
      const note = await apnProvider.send(note, deviceToken)
      console.log(note)
    } catch (err) {
      console.log(err)
    }
  }
}

export default ApnService

answered Nov 15, 2018 at 6:22

Aniket Pawar

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10 Comments

Dark Knight Over a year ago

Yes this will work but this is not ES-7 syntax. Am I right?

Aniket Pawar Over a year ago

@DarkKnight Async functions are introduced in ES2017. If you are using es6 then you need to compile it using babel or webpack

Dark Knight Over a year ago

This is my .babelrc

{   "presets": [     ["env", {       "targets": {         "node": 4.3       }     }]   ],   "env": {     "test": {       "plugins": ["istanbul"]     }   } }

Could you please let me know what I am missing here?

Aniket Pawar Over a year ago

Can you tell more about version of ecmascript and Node that you are using currently ?

Dark Knight Over a year ago

node version v8.9.3 and How do I check this version of ecmascript?

|

Drew Reese · Accepted Answer · 2018-11-15 07:01:33Z

3

async is a keyword to designate an asynchronous function, try

class ApnService {
    async sendNotification(deviceType, deviceToken, msg, type, id) { 
        try { 
            const note = await apnProvider.send(note, deviceToken) 
            console.log(note) 
        } catch (err) { 
            console.log(err) 
        } 
    }
 }
export default ApnService;

edited Nov 15, 2018 at 7:01

answered Nov 15, 2018 at 6:32

Drew Reese

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2 Comments

Gabriel L. Over a year ago

OP isn't trying to use async as a function, they're using it as a keyword. Look again: sendNotification = async (/* args */) => {

Drew Reese Over a year ago

Ah yes, narrow mobile screen.

Gabriel L. · Accepted Answer · 2018-11-15 06:27:14Z

1

class Foo {
    x = something
}

This assignment is an example of a class field. The usage of class property / class field syntax is currently at stage-3 in the TC39 process, meaning it is not yet in ECMAScript and not yet supported natively by all JS engines. It can be used via transpilers like Babel, but only if you configure and run such a transpiler yourself.

Luckily you don't need class field syntax to make a class method async, you can just use the async keyword.

class Foo {
    async myMethod () {/* ... */}
}

answered Nov 15, 2018 at 6:27

Gabriel L.

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1 Comment

Dark Knight Over a year ago

This is my .babelrc

{   "presets": [     ["env", {       "targets": {         "node": 4.3       }     }]   ],   "env": {     "test": {       "plugins": ["istanbul"]     }   } }

Could you please let me know what I am missing here?

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