Access Json arrays in javascript

Question

(It's actually for an assignment)

Hi, For hours I tried to solve my problem, I found some solutions, but it wasn't really what I wanted, and from my code I'm always hitting the same wall. thank you.

So I have a JSON file and a javascript file :

In my JSON file I have simple array of list of URL

    {
        "myUrlDatabase":[
            "https://www.francebleu.fr/emissions/ca-va-dans-le-bon-sens-en-poitou/poitou/quel-est-l-impact-du-changement-climatique-sur-les-migrations-d-oiseaux-marins",
            "https://www.terrafemina.com/article/environnement-pourquoi-2021-est-une-annee-cruciale-pour-agir_a357981/1",
            "https://www.franceinter.fr/monde/rechauffement-climatique-2020-est-l-annee-la-plus-chaude-jamais-enregistree-en-europe",
//more url
        ]}

I would like to access it in my javascript file, from what I have seen, I should use the fetch function, I followed a code on internet

fetch('/Data/url.json').then(function (response){
  return response.json();
}).then(function (obj){
  console.log(obj);
});

Indeed it print the file. but how can I make a var of the array ?

I would like later to use it in a random function

Math.randon() * {JSONFILE.length}

KooiInc · Accepted Answer · 2021-04-24 11:58:17Z

1

fetch delivers a Promise, so you have to use a (callback) lambda to use its result. Here's an example for that, mocking your random function for the keys of the result.

const postFetch = data => {
  if (!data.error) {
    const allKeys = Object.keys(data.results);
    const someKey = Math.floor(Math.random() * allKeys.length);
    console.log(`A pseudo random result => ${allKeys[someKey]}: ${
      data.results[allKeys[someKey]]}`);
    console.log(`The original json: ${JSON.stringify(data.results)}`);
  } else {
    console.log(`an error occured: ${data.message}`);
  }
}

fetch("https://api.sunrise-sunset.org/json?lat=53.22179255&lng=6.5582453664798")
  .then(r => r.json())
  .then(postFetch)
  //    ^ continue with the resulting object within your own function
  .catch(error => ({
    error: true,
    url,
    message: error.message
  }));

edited Apr 24, 2021 at 11:58

answered Apr 24, 2021 at 11:35

KooiInc

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Viktor W · Accepted Answer · 2021-04-24 11:26:09Z

1

You can access nested properties within the parsed JSON simply as fields within the obj parameter. The field which you want to access is myUrlDatabase.

var array = obj.myUrlDatabase
console.log(array.length)

answered Apr 24, 2021 at 11:26

Viktor W

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Gabriel Lupu · Accepted Answer · 2021-04-24 11:28:27Z

0

You can use the JSON.parse() method to transform json into a JavaScript data structure. Similar to your example:

// your response
const jsonInfo = "{ \"propArr\": [ \"string1\", \"string2\", \"string3\" ] }"
// use the parse() method
const getTheArray = JSON.parse(jsonInfo).propArr;

console.log(getTheArray);

Or if your data is already an object just do const whatIWant = receivedData.theArrayIWant and you'll have the whatIWant array.

answered Apr 24, 2021 at 11:28

Gabriel Lupu

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