Storing the retrieved JSON data in a variable

Question

Storing the retrieved JSON data in a variable

My current dilemma involves attempting to store JSON data in a variable, but I'm clearly missing something crucial. Initially, I successfully see the JSON displayed in the console as desired. However, upon subsequent attempts to access it later on, all that is returned is a promise. How can I properly save the JSON into a variable so that I can utilize the objects within the JSON at a later time?


var jsondata = fetch(url).then(
    function(u){ return u.json();}
  ).then(
    function(json){
      console.log(json);
    }
  )
console.log(jsondata);

javascript json fetch-api

Answer 1

Answer №1

The fetch API is Promise-based and will always result in a new Promise being returned, either resolved or rejected. There are various ways to handle the outcome.

Using Async/Await

async function fetchData(url) {
  const response = await fetch(url);

  return response.json();
}

const data = await fetchData(url);

console.log({ data })

With Callbacks

function fetchData(url, callback) {
  fetch(url)
    .then(response => response.json())
    .then(result => callback(result));
}

fetchData(url, (data) => console.log({ data }))

Answer 2

The fetch API is Promise-based and will always result in a new Promise being returned, either resolved or rejected. There are various ways to handle the outcome.

Using Async/Await

async function fetchData(url) {
  const response = await fetch(url);

  return response.json();
}

const data = await fetchData(url);

console.log({ data })

With Callbacks

function fetchData(url, callback) {
  fetch(url)
    .then(response => response.json())
    .then(result => callback(result));
}

fetchData(url, (data) => console.log({ data }))

Answer 3

Answer №2

const jsonDataReturned;    
fetch(url).then(
        function(response){ return response.json();}
      ).then(
        function(data){
          jsonDataReturned = data;
        }
      )

To clarify, the variable jsonDataReturned should be assigned the actual data once the promise is resolved, not the entire promise itself. Make sure you update your code accordingly to avoid any confusion.

Answer 4

const jsonDataReturned;    
fetch(url).then(
        function(response){ return response.json();}
      ).then(
        function(data){
          jsonDataReturned = data;
        }
      )

To clarify, the variable jsonDataReturned should be assigned the actual data once the promise is resolved, not the entire promise itself. Make sure you update your code accordingly to avoid any confusion.

Answer 5

Answer №3

To simplify the code, you can create a dedicated function outside the fetch function specifically to handle JSON data. In the example below, the fetch function retrieves the JSON object and then passes it to another function named "data_function." This allows us to easily manipulate and work with the JSON object within the "data_function".

//fetch function
fetch(url).then(
function(u){ return u.json();}
).then(
function(json){
data_function(json); //calling and passing json to another function data_function
}
)

//another functions
function data_function(data){
alert(data.length); 
}

Answer 6

To simplify the code, you can create a dedicated function outside the fetch function specifically to handle JSON data. In the example below, the fetch function retrieves the JSON object and then passes it to another function named "data_function." This allows us to easily manipulate and work with the JSON object within the "data_function".

//fetch function
fetch(url).then(
function(u){ return u.json();}
).then(
function(json){
data_function(json); //calling and passing json to another function data_function
}
)

//another functions
function data_function(data){
alert(data.length); 
}

Answer 7

Answer №4

Consider utilizing a callback function as a parameter to avoid exposing variables to the global scope.

function fetchFromAPI(url, callback){
  var data;
  fetch(url)
    .then(res => res.json())
    .then(response => data = response)
    .then(() => callback(data))
 }

fetchFromAPI('https://jsonplaceholder.typicode.com/posts', handleData);

function handleData(arrayOfObjects){
  var results = "";
  arrayOfObjects.forEach( (object) => {
    results += "<p> Id: " + object.id + "<ul>"
    Object.keys(object).forEach( (key) => {
        results += "<li>" + (key + ": " + object[key]) + "</li>";
    });
    results += "</ul> </p> <hr>"
  })
  results += "";
  document.getElementById("myDiv").innerHTML = results;
}

http://jsfiddle.net/5gch2yzw/

Answer 8

Consider utilizing a callback function as a parameter to avoid exposing variables to the global scope.

function fetchFromAPI(url, callback){
  var data;
  fetch(url)
    .then(res => res.json())
    .then(response => data = response)
    .then(() => callback(data))
 }

fetchFromAPI('https://jsonplaceholder.typicode.com/posts', handleData);

function handleData(arrayOfObjects){
  var results = "";
  arrayOfObjects.forEach( (object) => {
    results += "<p> Id: " + object.id + "<ul>"
    Object.keys(object).forEach( (key) => {
        results += "<li>" + (key + ": " + object[key]) + "</li>";
    });
    results += "</ul> </p> <hr>"
  })
  results += "";
  document.getElementById("myDiv").innerHTML = results;
}

http://jsfiddle.net/5gch2yzw/

Answer 9

Answer №5

One way to incorporate asynchronous functionality into your code is by defining a new async function called getData(). Within this example, data retrieved from a specified URL can be stored in a global variable for further use.

When the getData() function is invoked, it utilizes the fetchData() function to asynchronously retrieve city data from the designated URL. Once the data retrieval process is successful, the information is appended to the citiesData global variable, enabling you to access and utilize this data throughout your script.

async function fetchData(url) {
    const response = await fetch(url);
    const data = await response.json();
    return data;
}

const citiesData = [];
const url = 'https://gist.githubusercontent.com/Miserlou/c5cd8364bf9b2420bb29/raw/2bf258763cdddd704f8ffd3ea9a3e81d25e2c6f6/cities.json';

// Data fetching occurs just once
async function getData() {
    const data = await fetchData(url);
    citiesData.push(...data);
}

getData();

console.log(citiesData);

Answer 10

One way to incorporate asynchronous functionality into your code is by defining a new async function called getData(). Within this example, data retrieved from a specified URL can be stored in a global variable for further use.

When the getData() function is invoked, it utilizes the fetchData() function to asynchronously retrieve city data from the designated URL. Once the data retrieval process is successful, the information is appended to the citiesData global variable, enabling you to access and utilize this data throughout your script.

async function fetchData(url) {
    const response = await fetch(url);
    const data = await response.json();
    return data;
}

const citiesData = [];
const url = 'https://gist.githubusercontent.com/Miserlou/c5cd8364bf9b2420bb29/raw/2bf258763cdddd704f8ffd3ea9a3e81d25e2c6f6/cities.json';

// Data fetching occurs just once
async function getData() {
    const data = await fetchData(url);
    citiesData.push(...data);
}

getData();

console.log(citiesData);

Answer 11

Answer №6

exploring the latest top-level changes in modules (for nodejs version 18 and above)

let jsonData="";

const fetchJson = async () => {
    const response = await fetch("https://jsonplaceholder.typicode.com/posts/1")
    return await response.json()       
}

jsonData = await fetchJson()
console.log(jsonData.title)//prints: sunt aut facere repellat provident
//console.log(jsonData)

This code snippet is compatible with file.mjs, but not with file.js!

Answer 12

exploring the latest top-level changes in modules (for nodejs version 18 and above)

let jsonData="";

const fetchJson = async () => {
    const response = await fetch("https://jsonplaceholder.typicode.com/posts/1")
    return await response.json()       
}

jsonData = await fetchJson()
console.log(jsonData.title)//prints: sunt aut facere repellat provident
//console.log(jsonData)

This code snippet is compatible with file.mjs, but not with file.js!

Answer 13

Answer №7

The most straightforward method is to utilize async/await in your code.

To witness the magic, simply enter the following code into your Chrome developer console:

async function getUsers() {
            let response = await fetch('https://api.example.com/users')
            let users = await response.json()
            console.log(users)
    }

getUsers()

Answer 14

The most straightforward method is to utilize async/await in your code.

To witness the magic, simply enter the following code into your Chrome developer console:

async function getUsers() {
            let response = await fetch('https://api.example.com/users')
            let users = await response.json()
            console.log(users)
    }

getUsers()

Storing the retrieved JSON data in a variable

Answer №1

Using Async/Await

With Callbacks

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

Answer №7

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