Node.js async await in express












0














I'm building an endpoint /users which will return the contents in the Users.json file. I'm using aysnc/await feature.



var express = require('express');
var app = express();
var fs = require('fs');
var readFile = Promise.promisify(fs.readFile);
const util = require('util');

app.get('/users', async (req, res, next) => {
try {
const user = await readFile('./users.json');
return eval(user);
//res.send(JSON.parse(data));
// res.json(user);
} catch (e) {
//this will eventually be handled by your error handling middleware
next(e)
}
});
app.listen(3000,function(){
console.log("listening on port 3000");
});


This throws the below error




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'm using the npm 3.10.10 with node v6.11.3.



Can someone please guide where I have gone wrong?










share|improve this question


















  • 3




    Never ever use eval to parse JSON! In node.js, JSON.parse is always available.
    – Bergi
    Nov 20 at 9:00










  • What is Promise.promisify? Did you mean util.promisify?
    – Bergi
    Nov 20 at 9:01










  • I don't get any error using the code you posted.
    – Bergi
    Nov 20 at 9:03










  • Yup.. I meant util.promisify(), however I guess that's not causing this issue. @Bergi Was there any code change done apart from the util.promisify? I'm still getting the same error
    – technoJ
    Nov 20 at 9:04








  • 1




    Looks like node v6.11.3 does not support async/await syntax. Update it.
    – Bergi
    Nov 20 at 9:14
















0














I'm building an endpoint /users which will return the contents in the Users.json file. I'm using aysnc/await feature.



var express = require('express');
var app = express();
var fs = require('fs');
var readFile = Promise.promisify(fs.readFile);
const util = require('util');

app.get('/users', async (req, res, next) => {
try {
const user = await readFile('./users.json');
return eval(user);
//res.send(JSON.parse(data));
// res.json(user);
} catch (e) {
//this will eventually be handled by your error handling middleware
next(e)
}
});
app.listen(3000,function(){
console.log("listening on port 3000");
});


This throws the below error




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'm using the npm 3.10.10 with node v6.11.3.



Can someone please guide where I have gone wrong?










share|improve this question


















  • 3




    Never ever use eval to parse JSON! In node.js, JSON.parse is always available.
    – Bergi
    Nov 20 at 9:00










  • What is Promise.promisify? Did you mean util.promisify?
    – Bergi
    Nov 20 at 9:01










  • I don't get any error using the code you posted.
    – Bergi
    Nov 20 at 9:03










  • Yup.. I meant util.promisify(), however I guess that's not causing this issue. @Bergi Was there any code change done apart from the util.promisify? I'm still getting the same error
    – technoJ
    Nov 20 at 9:04








  • 1




    Looks like node v6.11.3 does not support async/await syntax. Update it.
    – Bergi
    Nov 20 at 9:14














0












0








0







I'm building an endpoint /users which will return the contents in the Users.json file. I'm using aysnc/await feature.



var express = require('express');
var app = express();
var fs = require('fs');
var readFile = Promise.promisify(fs.readFile);
const util = require('util');

app.get('/users', async (req, res, next) => {
try {
const user = await readFile('./users.json');
return eval(user);
//res.send(JSON.parse(data));
// res.json(user);
} catch (e) {
//this will eventually be handled by your error handling middleware
next(e)
}
});
app.listen(3000,function(){
console.log("listening on port 3000");
});


This throws the below error




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'm using the npm 3.10.10 with node v6.11.3.



Can someone please guide where I have gone wrong?










share|improve this question













I'm building an endpoint /users which will return the contents in the Users.json file. I'm using aysnc/await feature.



var express = require('express');
var app = express();
var fs = require('fs');
var readFile = Promise.promisify(fs.readFile);
const util = require('util');

app.get('/users', async (req, res, next) => {
try {
const user = await readFile('./users.json');
return eval(user);
//res.send(JSON.parse(data));
// res.json(user);
} catch (e) {
//this will eventually be handled by your error handling middleware
next(e)
}
});
app.listen(3000,function(){
console.log("listening on port 3000");
});


This throws the below error




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'm using the npm 3.10.10 with node v6.11.3.



Can someone please guide where I have gone wrong?







javascript node.js express async-await






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Nov 20 at 8:46









technoJ

1416




1416








  • 3




    Never ever use eval to parse JSON! In node.js, JSON.parse is always available.
    – Bergi
    Nov 20 at 9:00










  • What is Promise.promisify? Did you mean util.promisify?
    – Bergi
    Nov 20 at 9:01










  • I don't get any error using the code you posted.
    – Bergi
    Nov 20 at 9:03










  • Yup.. I meant util.promisify(), however I guess that's not causing this issue. @Bergi Was there any code change done apart from the util.promisify? I'm still getting the same error
    – technoJ
    Nov 20 at 9:04








  • 1




    Looks like node v6.11.3 does not support async/await syntax. Update it.
    – Bergi
    Nov 20 at 9:14














  • 3




    Never ever use eval to parse JSON! In node.js, JSON.parse is always available.
    – Bergi
    Nov 20 at 9:00










  • What is Promise.promisify? Did you mean util.promisify?
    – Bergi
    Nov 20 at 9:01










  • I don't get any error using the code you posted.
    – Bergi
    Nov 20 at 9:03










  • Yup.. I meant util.promisify(), however I guess that's not causing this issue. @Bergi Was there any code change done apart from the util.promisify? I'm still getting the same error
    – technoJ
    Nov 20 at 9:04








  • 1




    Looks like node v6.11.3 does not support async/await syntax. Update it.
    – Bergi
    Nov 20 at 9:14








3




3




Never ever use eval to parse JSON! In node.js, JSON.parse is always available.
– Bergi
Nov 20 at 9:00




Never ever use eval to parse JSON! In node.js, JSON.parse is always available.
– Bergi
Nov 20 at 9:00












What is Promise.promisify? Did you mean util.promisify?
– Bergi
Nov 20 at 9:01




What is Promise.promisify? Did you mean util.promisify?
– Bergi
Nov 20 at 9:01












I don't get any error using the code you posted.
– Bergi
Nov 20 at 9:03




I don't get any error using the code you posted.
– Bergi
Nov 20 at 9:03












Yup.. I meant util.promisify(), however I guess that's not causing this issue. @Bergi Was there any code change done apart from the util.promisify? I'm still getting the same error
– technoJ
Nov 20 at 9:04






Yup.. I meant util.promisify(), however I guess that's not causing this issue. @Bergi Was there any code change done apart from the util.promisify? I'm still getting the same error
– technoJ
Nov 20 at 9:04






1




1




Looks like node v6.11.3 does not support async/await syntax. Update it.
– Bergi
Nov 20 at 9:14




Looks like node v6.11.3 does not support async/await syntax. Update it.
– Bergi
Nov 20 at 9:14












2 Answers
2






active

oldest

votes


















2














Async/await is only available in Node versions 8 an up. Try using a newer Node version if possible.






share|improve this answer























  • should be version 8. Nodejs 7.5 supports async await only with the harmony flag
    – sheplu
    Nov 20 at 9:12












  • Indeed, updated the original answer
    – Johannes Obermair
    Nov 20 at 9:52










  • Thanks.. It did work after ugrading the node version to v10.13.0
    – technoJ
    Nov 20 at 9:58



















0














Instead of calling:



return eval(user);



You should call:



res.send(JSON.parse(user));



or



res.send(JSON.stringify(JSON.parse(user)));



and use bodyParser.json() middleware if returning an object.



Likewise in the catch block,



res.status(500).send(‘there was an error’);



and log the error to your console.



——-



Also, fs.readFile takes another param, the encoding. Use ‘utf-8’. It returns a buffer, not a string, if you leave it out.






share|improve this answer























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    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    2














    Async/await is only available in Node versions 8 an up. Try using a newer Node version if possible.






    share|improve this answer























    • should be version 8. Nodejs 7.5 supports async await only with the harmony flag
      – sheplu
      Nov 20 at 9:12












    • Indeed, updated the original answer
      – Johannes Obermair
      Nov 20 at 9:52










    • Thanks.. It did work after ugrading the node version to v10.13.0
      – technoJ
      Nov 20 at 9:58
















    2














    Async/await is only available in Node versions 8 an up. Try using a newer Node version if possible.






    share|improve this answer























    • should be version 8. Nodejs 7.5 supports async await only with the harmony flag
      – sheplu
      Nov 20 at 9:12












    • Indeed, updated the original answer
      – Johannes Obermair
      Nov 20 at 9:52










    • Thanks.. It did work after ugrading the node version to v10.13.0
      – technoJ
      Nov 20 at 9:58














    2












    2








    2






    Async/await is only available in Node versions 8 an up. Try using a newer Node version if possible.






    share|improve this answer














    Async/await is only available in Node versions 8 an up. Try using a newer Node version if possible.







    share|improve this answer














    share|improve this answer



    share|improve this answer








    edited Nov 20 at 9:19

























    answered Nov 20 at 9:10









    Johannes Obermair

    214




    214












    • should be version 8. Nodejs 7.5 supports async await only with the harmony flag
      – sheplu
      Nov 20 at 9:12












    • Indeed, updated the original answer
      – Johannes Obermair
      Nov 20 at 9:52










    • Thanks.. It did work after ugrading the node version to v10.13.0
      – technoJ
      Nov 20 at 9:58


















    • should be version 8. Nodejs 7.5 supports async await only with the harmony flag
      – sheplu
      Nov 20 at 9:12












    • Indeed, updated the original answer
      – Johannes Obermair
      Nov 20 at 9:52










    • Thanks.. It did work after ugrading the node version to v10.13.0
      – technoJ
      Nov 20 at 9:58
















    should be version 8. Nodejs 7.5 supports async await only with the harmony flag
    – sheplu
    Nov 20 at 9:12






    should be version 8. Nodejs 7.5 supports async await only with the harmony flag
    – sheplu
    Nov 20 at 9:12














    Indeed, updated the original answer
    – Johannes Obermair
    Nov 20 at 9:52




    Indeed, updated the original answer
    – Johannes Obermair
    Nov 20 at 9:52












    Thanks.. It did work after ugrading the node version to v10.13.0
    – technoJ
    Nov 20 at 9:58




    Thanks.. It did work after ugrading the node version to v10.13.0
    – technoJ
    Nov 20 at 9:58













    0














    Instead of calling:



    return eval(user);



    You should call:



    res.send(JSON.parse(user));



    or



    res.send(JSON.stringify(JSON.parse(user)));



    and use bodyParser.json() middleware if returning an object.



    Likewise in the catch block,



    res.status(500).send(‘there was an error’);



    and log the error to your console.



    ——-



    Also, fs.readFile takes another param, the encoding. Use ‘utf-8’. It returns a buffer, not a string, if you leave it out.






    share|improve this answer




























      0














      Instead of calling:



      return eval(user);



      You should call:



      res.send(JSON.parse(user));



      or



      res.send(JSON.stringify(JSON.parse(user)));



      and use bodyParser.json() middleware if returning an object.



      Likewise in the catch block,



      res.status(500).send(‘there was an error’);



      and log the error to your console.



      ——-



      Also, fs.readFile takes another param, the encoding. Use ‘utf-8’. It returns a buffer, not a string, if you leave it out.






      share|improve this answer


























        0












        0








        0






        Instead of calling:



        return eval(user);



        You should call:



        res.send(JSON.parse(user));



        or



        res.send(JSON.stringify(JSON.parse(user)));



        and use bodyParser.json() middleware if returning an object.



        Likewise in the catch block,



        res.status(500).send(‘there was an error’);



        and log the error to your console.



        ——-



        Also, fs.readFile takes another param, the encoding. Use ‘utf-8’. It returns a buffer, not a string, if you leave it out.






        share|improve this answer














        Instead of calling:



        return eval(user);



        You should call:



        res.send(JSON.parse(user));



        or



        res.send(JSON.stringify(JSON.parse(user)));



        and use bodyParser.json() middleware if returning an object.



        Likewise in the catch block,



        res.status(500).send(‘there was an error’);



        and log the error to your console.



        ——-



        Also, fs.readFile takes another param, the encoding. Use ‘utf-8’. It returns a buffer, not a string, if you leave it out.







        share|improve this answer














        share|improve this answer



        share|improve this answer








        edited Nov 20 at 9:12

























        answered Nov 20 at 9:07









        Steven Spungin

        6,58332230




        6,58332230






























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