JavaScript Variable does not change inside a function

Question

I've got a problem while programming some functions for Firebase functions. I want to find the User with the highest value stored in PFM and save his name in a Variable but the Variable does not change. What am I doing wrong?

Here is my Code:

var highestPFM = 0;
var userToSend = "";    

db.collection("users").get().then((snapshot) => {
        snapshot.forEach((doc) => {
        var data = doc.data();
            if(highestPFM > data["pfm"]){
                highestPFM = data["pfm"];
                userToSend = doc.id;
            }
        });
        console.log(prefixSendBottle + "User with highest PFM: " + userToSend);
        return userToSend;
    }).catch((err) => {
        response.send(err);
        console.log(err);
    });

@zero298 I don't think OP's issue is related to Async code. It's just a logical error in code. Plz check my answer. — Vivek Athalye
– Vivek Athalye, Commented Apr 3, 2018 at 18:30
@VivekAthalye I don't know, I worry anytime I see a variable have a scope broader than the scope of the asynchronous scope. Maybe it isn't related, but I'd like to see how highestPFM is used after the call to firebase. No matter what, we need more context. — zero298
– zero298, Commented Apr 3, 2018 at 18:31
@zero298 Yes, I can understand your concern and I agree with you on that. :) — Vivek Athalye
– Vivek Athalye, Commented Apr 3, 2018 at 18:33
While the scope of the variable could indeed be limited to the callback, that is not the cause of the problem here. I vote to reopen. — Frank van Puffelen
– Frank van Puffelen, Commented Apr 3, 2018 at 19:15

Vivek Athalye · Accepted Answer · 2018-04-03 18:29:22Z

2

You are checking if(highestPFM > data["pfm"]){... assuming you have only +ve values for pfm, this condition will never be true and hence the value of highestPFM will never change.

You need to change the condition to if(data["pfm"] > highestPFM){.

answered Apr 3, 2018 at 18:29

Vivek Athalye

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1 Comment

Philipp Honsel Over a year ago

Ouh that was a really stupid mistake from me. That for the advice!

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