What is the best way to merge two sets of data in JavaScript?

Question

What is the best way to merge two sets of data in JavaScript?

There are two sources from which I am retrieving data.
Once the data is fetched, I need to merge them into a single source.
Here's an example;

//data structure looks like:
//from url1
{
    "data": [
        {
            "id": 7,
            "email": "<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="d8b5b1bbb0b9bdb4f6b4b9afabb7b698aabda9aabdabf6b1b6">[email protected]</a>",
            "first_name": "Michael",
            "last_name": "Lawson"
        },
    ]
}

//from url2
{
    "data": [
        {
            "id": 8,
            "email": "<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="a0cc...">">[email protected]</a>"
            "first_name": "Lindsay",
            "last_name": "Ferguson"
        }
    ]
}

Upon merging, the desired outcome for the data:

{
    "data": [
        {
            "id": 7,
            "email": "<a href="/cdn-cgi/l/email-protection" class="__cf_email_...">">[email protected]</a>"
            "first_name": "Michael",
            "last_name": "Lawson"
        },
        {
            "id": 8,
            "email": "<a href="/cdn-cgi/l/email-protection" class="__cf_email_...">">[email protected]</a>"
            "first_name": "Lindsay",
            "last_name": "Ferguson"
        }
    ]
}

Code snippet:

 const url1 = "https://reqres.in/api/users"; 
 const url2 = "https://reqres.in/api/users?page=2";

//store the data from url1
const data1 = fetch(url1).then(result=>{
return result.data;
})

//store the data from url2
const data2 = fetch(url2).then(result=>{
return result.data;
})

I attempted using Object.assign(), however it did not yield the expected results.

const data = Object.assign(data1, data2); // only retrieves data from data1, while data2 remains missing
console.log(data);

javascript

Answer 1

Answer №1

give this a try

 const url1 = "https://reqres.in/api/users"; 
     const url2 = "https://reqres.in/api/users?page=2";

    //retrieve information from url1
    async function fetchData(){

        
    let response1 = await fetch(url1);
    let response2 = await fetch(url2);

    
    if (response1.status === 200 && response2.status === 200) {
        const data1 = await response1.json();
        const data2 = await response2.json();
        // handle the received data

        const combinedData = [...data1.data, ...data2.data];  // it only retrieves data from data1, missing out on data2
        console.log(combinedData); 
    }




    }

    fetchData();

Answer 2

give this a try

 const url1 = "https://reqres.in/api/users"; 
     const url2 = "https://reqres.in/api/users?page=2";

    //retrieve information from url1
    async function fetchData(){

        
    let response1 = await fetch(url1);
    let response2 = await fetch(url2);

    
    if (response1.status === 200 && response2.status === 200) {
        const data1 = await response1.json();
        const data2 = await response2.json();
        // handle the received data

        const combinedData = [...data1.data, ...data2.data];  // it only retrieves data from data1, missing out on data2
        console.log(combinedData); 
    }




    }

    fetchData();

Answer 3

Answer №2

Here's my suggested approach:

Create an array to store the URLs.
Utilize async/await for a smoother process.
Apply map on the array to generate a new array of promises.
Wait until all promises are resolved using await.
Convert JSON data into JavaScript objects.
Return an object that consolidates all data properties from multiple objects into one with the help of flatMap.

const urls = ['https://reqres.in/api/users','https://reqres.in/api/users?page=2'];

// Pass in the array to the function
async function getData(urls) {

  try {

    // `map` over the array to create an array of promises
    const promises = urls.map(url => fetch(url));

    // Wait for the responses to return
    const responses = await Promise.all(promises);

    // Use `map` again to parse the JSON
    // `.json()` returns a new promise so we have to
    //  use `Promise.all` again to wait for them all to resolve
    const data = await Promise.all(responses.map(res => res.json()));

    // Finally return an object that combines the data
    // within one data property
    return { data: data.flatMap(obj => obj.data) };
  
  } catch(err) {
    return err;
  }

}

(async () => {
  console.log(await getData(urls));
})();

Answer 4

Here's my suggested approach:

Create an array to store the URLs.
Utilize async/await for a smoother process.
Apply map on the array to generate a new array of promises.
Wait until all promises are resolved using await.
Convert JSON data into JavaScript objects.
Return an object that consolidates all data properties from multiple objects into one with the help of flatMap.

const urls = ['https://reqres.in/api/users','https://reqres.in/api/users?page=2'];

// Pass in the array to the function
async function getData(urls) {

  try {

    // `map` over the array to create an array of promises
    const promises = urls.map(url => fetch(url));

    // Wait for the responses to return
    const responses = await Promise.all(promises);

    // Use `map` again to parse the JSON
    // `.json()` returns a new promise so we have to
    //  use `Promise.all` again to wait for them all to resolve
    const data = await Promise.all(responses.map(res => res.json()));

    // Finally return an object that combines the data
    // within one data property
    return { data: data.flatMap(obj => obj.data) };
  
  } catch(err) {
    return err;
  }

}

(async () => {
  console.log(await getData(urls));
})();

Answer 5

Answer №3

If you are attempting to combine promises that resolve to arrays, remember to await each promise and utilize the spread operator to merge their elements. In order to read and parse the response, make sure to use the json method which also returns a promise. To handle this properly, I enclosed the awaits within an async IIFE (Immediately Invoked Function Expression) because using await is not allowed in non-async functions or in the global scope.

const url1 = "https://reqres.in/api/users"; 
const url2 = "https://reqres.in/api/users?page=2";

// store promise containing data from url1
const data1 = fetch(url1)
              .then(result => result.json())
              .then(result => result.data);

// store promise containing data from url2
const data2 = fetch(url2)
              .then(result => result.json())
              .then(result => result.data);

(async () => {
  const data = [...await data1, ...await data2];
  console.log(data); 
})();

Answer 6

If you are attempting to combine promises that resolve to arrays, remember to await each promise and utilize the spread operator to merge their elements. In order to read and parse the response, make sure to use the json method which also returns a promise. To handle this properly, I enclosed the awaits within an async IIFE (Immediately Invoked Function Expression) because using await is not allowed in non-async functions or in the global scope.

const url1 = "https://reqres.in/api/users"; 
const url2 = "https://reqres.in/api/users?page=2";

// store promise containing data from url1
const data1 = fetch(url1)
              .then(result => result.json())
              .then(result => result.data);

// store promise containing data from url2
const data2 = fetch(url2)
              .then(result => result.json())
              .then(result => result.data);

(async () => {
  const data = [...await data1, ...await data2];
  console.log(data); 
})();

Answer 7

Answer №4

If you want to merge all the elements from two arrays, one way is to utilize the spread operator as shown below:

const mergedArray = [...array1, ...array2];

Alternatively, you can achieve the same result using the concat method:

const mergedArray = array1.concat(array2);

Answer 8

If you want to merge all the elements from two arrays, one way is to utilize the spread operator as shown below:

const mergedArray = [...array1, ...array2];

Alternatively, you can achieve the same result using the concat method:

const mergedArray = array1.concat(array2);

Answer 9

Answer №5

Your data fetching method is not yet fully optimized.

The following code will return a Response object containing details about the response received.

fetch('https://reqres.in/api/users').then(response => console.log(response))

To properly retrieve the data, you should modify your code to:

fetch('https://reqres.in/api/users').then(response => response.json()).then(data => console.log(data))

Answer 10

Your data fetching method is not yet fully optimized.

The following code will return a Response object containing details about the response received.

fetch('https://reqres.in/api/users').then(response => console.log(response))

To properly retrieve the data, you should modify your code to:

fetch('https://reqres.in/api/users').then(response => response.json()).then(data => console.log(data))

Answer 11

Answer №6

//Here is the data structure containing information from two different URLs:
//Data from url1
const url = {
    "data": [
                {
            "id": 7,
            "email": "<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="513c38323930343d7f3d3026223e3f112334202334227f383f">[email protected]</a>",
            "first_name": "Michael",
            "last_name": "Lawson"
        },
    ]
}

//Data from url2
const urlTwo = {
    "data": [
        {
            "id": 8,
            "email": "<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="dcb0b5b2b8afbda5f2bab9aebba9afb3b29caeb9adaeb9aff2b5b2">[email protected]</a>",
            "first_name": "Lindsay",
            "last_name": "Ferguson"
        }
    ]
}

let combinedData = [...url.data, ...urlTwo.data];
console.log(combinedData);

Try implementing the above code snippet.

//Here is the updated data structure with email protection in place:
//Data from url1
const url = {
    "data": [
                {
            "id": 7,
            "email": "<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="cfa2a6aca7aeaaa3e1a3aeb8bca0a18fbdaabebdaabce1a6a1">[email protected]</a>",
            "first_name": "Michael",
            "last_name": "Lawson"
        },
    ]
}

//Data from url2
const urlTwo = {
    "data": [
        {
            "id": 8,
            "email": "<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="d0bcb9beb4a3b1a9feb6b5a2b7a5a3bfbe90a2b5a1a2b5a3feb9be">[email protected]</a>",
            "first_name": "Lindsay",
            "last_name": "Ferguson"
        }
    ]
}

let combinedData = [...url.data, ...urlTwo.data];
console.log(combinedData);

If you encounter any issues, feel free to ask for assistance.

Answer 12

//Here is the data structure containing information from two different URLs:
//Data from url1
const url = {
    "data": [
                {
            "id": 7,
            "email": "<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="513c38323930343d7f3d3026223e3f112334202334227f383f">[email protected]</a>",
            "first_name": "Michael",
            "last_name": "Lawson"
        },
    ]
}

//Data from url2
const urlTwo = {
    "data": [
        {
            "id": 8,
            "email": "<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="dcb0b5b2b8afbda5f2bab9aebba9afb3b29caeb9adaeb9aff2b5b2">[email protected]</a>",
            "first_name": "Lindsay",
            "last_name": "Ferguson"
        }
    ]
}

let combinedData = [...url.data, ...urlTwo.data];
console.log(combinedData);

Try implementing the above code snippet.

//Here is the updated data structure with email protection in place:
//Data from url1
const url = {
    "data": [
                {
            "id": 7,
            "email": "<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="cfa2a6aca7aeaaa3e1a3aeb8bca0a18fbdaabebdaabce1a6a1">[email protected]</a>",
            "first_name": "Michael",
            "last_name": "Lawson"
        },
    ]
}

//Data from url2
const urlTwo = {
    "data": [
        {
            "id": 8,
            "email": "<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="d0bcb9beb4a3b1a9feb6b5a2b7a5a3bfbe90a2b5a1a2b5a3feb9be">[email protected]</a>",
            "first_name": "Lindsay",
            "last_name": "Ferguson"
        }
    ]
}

let combinedData = [...url.data, ...urlTwo.data];
console.log(combinedData);

If you encounter any issues, feel free to ask for assistance.

What is the best way to merge two sets of data in JavaScript?

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

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