Calling (and catching) multiple promises











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0
down vote

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I am trying to run below code (modified from this link):



let cnt = 1;

var prom = () => new Promise(
function (resolve, reject) {
try {
console.log('enter promise ' + cnt);
if (Math.random() < 0.5) throw new Error('error in promise ' + cnt);
resolve('done in promise ' + cnt);
}
catch (e) {
reject(e);
}
finally{
cnt++;
}
}
);

prom()
.then(prom())
.then(function (fulfilled) {
console.log('all done: ' + fulfilled);
})
.catch(function (error) {
console.log(error.message);
});


Basically I am trying to achieve a catch-all behaviour, i.e. if either promise fails, catch and stop processing. However can't achieve. What am I missing?










share|improve this question






















  • What is happening? Are you getting an error? What error?
    – iagowp
    Nov 21 at 22:54










  • Do not pass a promise to then(). Pass a callback function instead, e.g. .then(prom).
    – Bergi
    Nov 21 at 22:57










  • this looks like the issue; can you make it an answer?
    – paul simmons
    Nov 21 at 22:58










  • Which example exactly from the linked page did you use, and what and why did you modify?
    – Bergi
    Nov 21 at 22:59

















up vote
0
down vote

favorite












I am trying to run below code (modified from this link):



let cnt = 1;

var prom = () => new Promise(
function (resolve, reject) {
try {
console.log('enter promise ' + cnt);
if (Math.random() < 0.5) throw new Error('error in promise ' + cnt);
resolve('done in promise ' + cnt);
}
catch (e) {
reject(e);
}
finally{
cnt++;
}
}
);

prom()
.then(prom())
.then(function (fulfilled) {
console.log('all done: ' + fulfilled);
})
.catch(function (error) {
console.log(error.message);
});


Basically I am trying to achieve a catch-all behaviour, i.e. if either promise fails, catch and stop processing. However can't achieve. What am I missing?










share|improve this question






















  • What is happening? Are you getting an error? What error?
    – iagowp
    Nov 21 at 22:54










  • Do not pass a promise to then(). Pass a callback function instead, e.g. .then(prom).
    – Bergi
    Nov 21 at 22:57










  • this looks like the issue; can you make it an answer?
    – paul simmons
    Nov 21 at 22:58










  • Which example exactly from the linked page did you use, and what and why did you modify?
    – Bergi
    Nov 21 at 22:59















up vote
0
down vote

favorite









up vote
0
down vote

favorite











I am trying to run below code (modified from this link):



let cnt = 1;

var prom = () => new Promise(
function (resolve, reject) {
try {
console.log('enter promise ' + cnt);
if (Math.random() < 0.5) throw new Error('error in promise ' + cnt);
resolve('done in promise ' + cnt);
}
catch (e) {
reject(e);
}
finally{
cnt++;
}
}
);

prom()
.then(prom())
.then(function (fulfilled) {
console.log('all done: ' + fulfilled);
})
.catch(function (error) {
console.log(error.message);
});


Basically I am trying to achieve a catch-all behaviour, i.e. if either promise fails, catch and stop processing. However can't achieve. What am I missing?










share|improve this question













I am trying to run below code (modified from this link):



let cnt = 1;

var prom = () => new Promise(
function (resolve, reject) {
try {
console.log('enter promise ' + cnt);
if (Math.random() < 0.5) throw new Error('error in promise ' + cnt);
resolve('done in promise ' + cnt);
}
catch (e) {
reject(e);
}
finally{
cnt++;
}
}
);

prom()
.then(prom())
.then(function (fulfilled) {
console.log('all done: ' + fulfilled);
})
.catch(function (error) {
console.log(error.message);
});


Basically I am trying to achieve a catch-all behaviour, i.e. if either promise fails, catch and stop processing. However can't achieve. What am I missing?







node.js promise






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Nov 21 at 22:47









paul simmons

2,453104672




2,453104672












  • What is happening? Are you getting an error? What error?
    – iagowp
    Nov 21 at 22:54










  • Do not pass a promise to then(). Pass a callback function instead, e.g. .then(prom).
    – Bergi
    Nov 21 at 22:57










  • this looks like the issue; can you make it an answer?
    – paul simmons
    Nov 21 at 22:58










  • Which example exactly from the linked page did you use, and what and why did you modify?
    – Bergi
    Nov 21 at 22:59




















  • What is happening? Are you getting an error? What error?
    – iagowp
    Nov 21 at 22:54










  • Do not pass a promise to then(). Pass a callback function instead, e.g. .then(prom).
    – Bergi
    Nov 21 at 22:57










  • this looks like the issue; can you make it an answer?
    – paul simmons
    Nov 21 at 22:58










  • Which example exactly from the linked page did you use, and what and why did you modify?
    – Bergi
    Nov 21 at 22:59


















What is happening? Are you getting an error? What error?
– iagowp
Nov 21 at 22:54




What is happening? Are you getting an error? What error?
– iagowp
Nov 21 at 22:54












Do not pass a promise to then(). Pass a callback function instead, e.g. .then(prom).
– Bergi
Nov 21 at 22:57




Do not pass a promise to then(). Pass a callback function instead, e.g. .then(prom).
– Bergi
Nov 21 at 22:57












this looks like the issue; can you make it an answer?
– paul simmons
Nov 21 at 22:58




this looks like the issue; can you make it an answer?
– paul simmons
Nov 21 at 22:58












Which example exactly from the linked page did you use, and what and why did you modify?
– Bergi
Nov 21 at 22:59






Which example exactly from the linked page did you use, and what and why did you modify?
– Bergi
Nov 21 at 22:59














2 Answers
2






active

oldest

votes

















up vote
0
down vote



accepted










.then() takes a callback as an argument and you gave it the returned Promise itself.



Use .then(prom) instead.






share|improve this answer




























    up vote
    0
    down vote













    Use Promise.all



    return Promise.all([
    prom(),
    prom()
    ])
    .then(([fullfilled1, fulfilled2]) => {
    console.log('all done: ' + fulfilled1 + ' ' + fulfilled2);
    })
    .catch(err => {
    console.log(error.message);
    });


    If one fails, everyone fails.






    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








      up vote
      0
      down vote



      accepted










      .then() takes a callback as an argument and you gave it the returned Promise itself.



      Use .then(prom) instead.






      share|improve this answer

























        up vote
        0
        down vote



        accepted










        .then() takes a callback as an argument and you gave it the returned Promise itself.



        Use .then(prom) instead.






        share|improve this answer























          up vote
          0
          down vote



          accepted







          up vote
          0
          down vote



          accepted






          .then() takes a callback as an argument and you gave it the returned Promise itself.



          Use .then(prom) instead.






          share|improve this answer












          .then() takes a callback as an argument and you gave it the returned Promise itself.



          Use .then(prom) instead.







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Nov 21 at 23:04









          Sebastian Speitel

          4,0622425




          4,0622425
























              up vote
              0
              down vote













              Use Promise.all



              return Promise.all([
              prom(),
              prom()
              ])
              .then(([fullfilled1, fulfilled2]) => {
              console.log('all done: ' + fulfilled1 + ' ' + fulfilled2);
              })
              .catch(err => {
              console.log(error.message);
              });


              If one fails, everyone fails.






              share|improve this answer

























                up vote
                0
                down vote













                Use Promise.all



                return Promise.all([
                prom(),
                prom()
                ])
                .then(([fullfilled1, fulfilled2]) => {
                console.log('all done: ' + fulfilled1 + ' ' + fulfilled2);
                })
                .catch(err => {
                console.log(error.message);
                });


                If one fails, everyone fails.






                share|improve this answer























                  up vote
                  0
                  down vote










                  up vote
                  0
                  down vote









                  Use Promise.all



                  return Promise.all([
                  prom(),
                  prom()
                  ])
                  .then(([fullfilled1, fulfilled2]) => {
                  console.log('all done: ' + fulfilled1 + ' ' + fulfilled2);
                  })
                  .catch(err => {
                  console.log(error.message);
                  });


                  If one fails, everyone fails.






                  share|improve this answer












                  Use Promise.all



                  return Promise.all([
                  prom(),
                  prom()
                  ])
                  .then(([fullfilled1, fulfilled2]) => {
                  console.log('all done: ' + fulfilled1 + ' ' + fulfilled2);
                  })
                  .catch(err => {
                  console.log(error.message);
                  });


                  If one fails, everyone fails.







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered Nov 21 at 23:37









                  dvsoukup

                  1,012923




                  1,012923






























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