outside for loop var value is undefined

[Catia Matos]

0down votefavorite

I'm facing a problem with a value where inside my for cycle it has values like "179" and outside i get always undefined. Why? var countRepetidos; if(obj.data.list!={} && obj.data.list.length>0){ var aux = obj.data["list"]; countRepetidos=0; for(var i=0;i<aux.length;i++){ Database.Probing.getMacAdress(aux[i]).then(function(data){ if(data.count>0){ countRepetidos++; console.log("count repetidos 1",countRepetidos); // value 116 } }); } return resolve(countRepetidos); } console.log("count repetidos 2",countRepetidos); // value undefined log : 3|wscontro | count repetidos 1 116 3|wscontro | count repetidos 2 undefined I try instead of use resolve, use callback but nothing... I saw other answers in javascript but for node.js I cant resolve this problem... I saw the link refering thus question as a duplicate but cant figure out a solution to this case.

[tpx1]

Hi,

to mentions for you problem. Do it like this:

let countRepetidos = 0;
const count = (data) => {

if(data.count>0){
countRepetidos++;
console.log("count repetidos 1",countRepetidos); // value 116
}

};

Promise.all(aux.map((val) =>
Database.Probing.getMacAdress(val).then(count)).then(() =>
resolve(countRepetidos))

Your problem is a classical async problem. You mix async and sync stuff.
What we do is, to map your aux values to the resolver values from the
query. Now we are able to watch, if all resolver are are finished by
Promise.all and then handle your counting.

A much fancier implementation is this.

const count = (data) => {
return data.count > 0 ? 1 : 0;
};

Promise.all(aux.map((val) =>
Database.Probing.getMacAdress(val).then(count)).then((data) =>
resolve(data.reduce((p,c) => p+c,1));

You also should use Array.isArray(obj.data.list) instead of this -
obj.data.list!={} - in the if statement.

Hope it will help to solve your problem.

Thomas


Am 21.07.2017 um 13:54 schrieb Catia Matos:
>
> 0down votefavorite
> <https://stackoverflow.com/questions/45236919/outside-for-loop-var-value-is-undefined#>

>
>
> I'm facing a problem with a value where inside my for cycle it has
> values like "179" and outside i get always undefined. Why?
>
> |varcountRepetidos;if(obj.data.list!={}&&obj.data.list.length>0){varaux

> =obj.data["list"];countRepetidos=0;for(vari=0;i<aux.length;i++){Database.Probing.getMacAdress(aux[i]).then(function(data){if(data.count>0){countRepetidos++;console.log("count

> repetidos 1",countRepetidos);// value

> 116}});}returnresolve(countRepetidos);}console.log("count repetidos

> 2",countRepetidos);// value undefined|
>
> log :
>
> |3|wscontro |count repetidos 11163|wscontro |count repetidos 2undefined|
>
> I try instead of use resolve, use callback but nothing... I saw other
> answers in javascript but for node.js I cant resolve this problem... I
> saw the link refering thus question as a duplicate but cant figure out a
> solution to this case.
>

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[DaneiL]

You have to put this line

console.log("count repetidos 2",countRepetidos);    // value undefined

before the return function

return resolve(countRepetidos);

var countRepetidos;
if(obj.data.list!={} && obj.data.list.length>0){    
    var aux = obj.data["list"];
    countRepetidos=0;
    for(var i=0;i<aux.length;i++){                              
       Database.Probing.getMacAdress(aux[i]).then(function(data){
            if(data.count>0){
               countRepetidos++;  
               console.log("count repetidos 1",countRepetidos); // value 116
            }                                   
        });
    }

    console.log("count repetidos 2",countRepetidos); 

    return resolve(countRepetidos);
}   

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[]'s

[Zlatko]

The problem is that your last console.log line runs before anything else.

I don't see the rest of the code, but I suspect if you move your return resolve(countRepetidos); 2 lines up (right behind that if(data.count>0) {} block), your promise will resolve proper value.

Likewise, if you put the console log there, it's going to work.