promise in loop in node.js

Question

Promise.all(function(){
    for(var numb in req.body){
        console.log(numb+":"+req.body[numb]);
        checkValue(numb,function(err,result){
            if(result){
                console.log(result);
                send[result]="true";
                console.log(send);
            }
            if(err){console.log(err+"not");}
        });
    }   
}).then(res.json(send));

I want to execute the for loop first and then send the data back. I am trying to use promise.all but I am not sure if its correct. could someone help me out?

Please format/indent your code properly to make it readable. — jfriend00
– jfriend00, Commented Apr 23, 2016 at 17:25
You pass an array of promises to Promise.all(). You do not pass a function to Promise.all(). There are also no asynchronous operations in the code you show so there is no reason to use promises at all. You can just code a regular loop. — jfriend00
– jfriend00, Commented Apr 23, 2016 at 17:25

YakovL · Accepted Answer · 2017-12-29 18:43:03Z

34

If you're using Promises, check out this

you can just fix this by doing the following:

var promises = [];

for(var numb in req.body)
{
    promises.push(checkValue(numb));
}

Promise.all(promises)    
 .then(function(data){ /* do stuff when success */ })
 .catch(function(err){ /* error handling */ });

function checkValue(numb){
 return new Promise(function(resolve, reject){
  // place here your logic
  // return resolve([result object]) in case of success
  // return reject([error object]) in case of error
});

edited Dec 29, 2017 at 18:43

YakovL

8,44813 gold badges74 silver badges117 bronze badges

answered Apr 23, 2016 at 9:58

smeedten

3533 silver badges5 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Little geek Over a year ago

Great answer! Just for those of us who don't know Promise.all: if it fulfills it returns an array of the values from the fulfilled promises in the same order as defined in the iterable.

Collectives™ on Stack Overflow

promise in loop in node.js

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related