Having trouble retrieving the value of an object within an array

Question

Having trouble retrieving the value of an object within an array

{"-L0bFExUeZXB3-MUXCda":{"Comment":"GOOD","Date":"18 December","User":"OlaNord"}}

{"-L0bFCJh5SPUOWMjTRKu":{"Comment":"ok","Date":"18 December","User":"OlaNord"}}

{"-L0bFA2uzsGDizxxzN1p":{"Comment":"wewwe","Date":"18 December","User":"OlaNord"}}

Within this array containing objects, there are various values that I need to access. However, when attempting to retrieve the key name, it returns undefined.

Below is the code snippet:

// Path for selected category
var categoryRef = firebase.database().ref("forum/" + currentCategory);

categoryRef.once("value", function(snapshot) {
    firebase.auth().onAuthStateChanged(user => {
        var userKey = user.uid;
        var commentsArr = [];

        for (var commentKey in snapshot.val()) {
            var postComments = snapshot.val()[commentKey]['comments'];
            commentsArr.push(postComments);
        }
    })
})

https://i.sstatic.net/gDCu4.png

javascript arrays json

Answer 1

Answer №1

If you want to access the comments in the array provided in the question, you can do so by using the following code snippet:

var data = [{
        "-L0bFExUeZXB3-MUXCda": {
            "Comment": "GOOD",
            "Date": "18 December",
            "User": "OlaNord"
        }
    },

    {
        "-L0bFCJh5SPUOWMjTRKu": {
            "Comment": "ok",
            "Date": "18 December",
            "User": "OlaNord"
        }
    },

    {
        "-L0bFA2uzsGDizxxzN1p": {
            "Comment": "wewwe",
            "Date": "18 December",
            "User": "OlaNord"
        }
    }
]

var postComments = [];
for (var key of data) {
    for (var values in key) {
        console.log(key[values].Comment) //access the comment
        postComments.push(key[values].Comment);
    }
}

console.log(postComments);

Answer 2

If you want to access the comments in the array provided in the question, you can do so by using the following code snippet:

var data = [{
        "-L0bFExUeZXB3-MUXCda": {
            "Comment": "GOOD",
            "Date": "18 December",
            "User": "OlaNord"
        }
    },

    {
        "-L0bFCJh5SPUOWMjTRKu": {
            "Comment": "ok",
            "Date": "18 December",
            "User": "OlaNord"
        }
    },

    {
        "-L0bFA2uzsGDizxxzN1p": {
            "Comment": "wewwe",
            "Date": "18 December",
            "User": "OlaNord"
        }
    }
]

var postComments = [];
for (var key of data) {
    for (var values in key) {
        console.log(key[values].Comment) //access the comment
        postComments.push(key[values].Comment);
    }
}

console.log(postComments);

Answer 3

Answer №2

// Retrieving comments for selected category
var categoryReference = firebase.database().ref("forum/" + currentCategory);

categoryReference.once("value", function(dataSnapshot) {
    firebase.auth().onAuthStateChanged(currentUser => {
        var userKey = currentUser.uid;
        var allComments = [];

        for (var commentKey in dataSnapshot.val()) {
            var commentValue = dataSnapshot.val()[commentKey]['Comment'];
             //Changing the key name
            allComments.push(commentValue);
        }
    })
})

Answer 4

// Retrieving comments for selected category
var categoryReference = firebase.database().ref("forum/" + currentCategory);

categoryReference.once("value", function(dataSnapshot) {
    firebase.auth().onAuthStateChanged(currentUser => {
        var userKey = currentUser.uid;
        var allComments = [];

        for (var commentKey in dataSnapshot.val()) {
            var commentValue = dataSnapshot.val()[commentKey]['Comment'];
             //Changing the key name
            allComments.push(commentValue);
        }
    })
})

Answer 5

Answer №3

If you want to retrieve the values associated with a key, you can utilize the Object.values method.

var information = [{"-L0bFExUeZXB3-MUXCda":{"Comment":"GOOD","Date":"18 December","User":"OlaNord"}},{"-L0bFCJh5SPUOWMjTRKu":{"Comment":"ok","Date":"18 December","User":"OlaNord"}},{"-L0bFA2uzsGDizxxzN1p":{"Comment":"wewwe","Date":"18 December","User":"OlaNord"}}];
var output = information.reduce((res,obj) => res.concat(Object.values(obj).map(({Comment}) => Comment)),[]);
console.log(output);

Answer 6

If you want to retrieve the values associated with a key, you can utilize the Object.values method.

var information = [{"-L0bFExUeZXB3-MUXCda":{"Comment":"GOOD","Date":"18 December","User":"OlaNord"}},{"-L0bFCJh5SPUOWMjTRKu":{"Comment":"ok","Date":"18 December","User":"OlaNord"}},{"-L0bFA2uzsGDizxxzN1p":{"Comment":"wewwe","Date":"18 December","User":"OlaNord"}}];
var output = information.reduce((res,obj) => res.concat(Object.values(obj).map(({Comment}) => Comment)),[]);
console.log(output);

Having trouble retrieving the value of an object within an array

Answer №1

Answer №2

Answer №3

Similar questions

Can Angular toggle visibility of static HTML content?

Volley network image viewer and HTTP request headers

Is it possible to create a horizontal navigation bar with buttons that scrolls when media queries are activated? I am looking for a solution using HTML,CSS, JavaScript, and Bootstrap

The Model Viewer module is unable to load the three-dimensional model

Creating routes in Node.js after setting up middleware

I'm having trouble grasping the concept of this asynchronous behavior

Create index request contains an unidentified key [_index]

accessing specific data within a JSON object using its index

Addressing Equity Concerns within JavaScript Programming

Reactjs may have an undefined value for Object

unable to access POST information

The Google Maps application is having trouble zooming in

When using Multer for file upload, the req.body returns as an empty object while req.file is undefined

The exception `com.fasterxml.jackson.databind.exc.MismatchedInputException` occurs when unable to create an instance of `java.util.LinkedHashMap`

Creating multiple countdowns in AngularJS using ng-repeat is a handy feature to have

The combination of select2 and jsonform is not functioning properly

Leveraging the outcome of a Promise within webpack's configuration file

transmitting a CSV file from PHP to the web browser

Creating a sequence of HTTP calls that call upon themselves using RxJs operators

Display/Conceal a div using CSS in React JS/Redux