Converting JSON value into JavaScript array - Stack Overflow

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I want to convert a JSON string into a set of array containing the values from the JSON. after json.stringify(jsonmybe) and alert it display [{"role":"noi_user"},{"role":"bert_user"}] (which i saw as a JSON). I want to get the noi_user and bert_user and set them into a javascript array. something like ['noi_user','bert_user'] with quotes in each value.

I did the var stringy = json.parse() and the alert showing [object Object]. and further add this lines

for (var i = 0; i < stringy.length; i++) {
    arr.push(stringy[i]['role']);}

and the arr I get was a value with ma when in alert but the ma missing as i display them in the text field and it bees a long string like noi_userbert_user

What I really want is from [{"role":"noi_user"},{"role":"bert_user"}] to ['noi_user','bert_user']

I want to convert a JSON string into a set of array containing the values from the JSON. after json.stringify(jsonmybe) and alert it display [{"role":"noi_user"},{"role":"bert_user"}] (which i saw as a JSON). I want to get the noi_user and bert_user and set them into a javascript array. something like ['noi_user','bert_user'] with quotes in each value.

I did the var stringy = json.parse() and the alert showing [object Object]. and further add this lines

for (var i = 0; i < stringy.length; i++) {
    arr.push(stringy[i]['role']);}

and the arr I get was a value with ma when in alert but the ma missing as i display them in the text field and it bees a long string like noi_userbert_user

What I really want is from [{"role":"noi_user"},{"role":"bert_user"}] to ['noi_user','bert_user']

• javascript
• arrays
• json

Share Improve this question Follow edited Jul 19, 2019 at 18:16 Mike Poole 2,05355 gold badges3232 silver badges4545 bronze badges asked Jul 19, 2019 at 7:23 Abner Stan.Abner Stan. 12111 silver badge1414 bronze badges 3

• as an FYI the quote type (' and " are identical in JS) are irrelevant – Liam Commented Jul 19, 2019 at 7:30
• If you want JSON (which has different rules about quotes) then ['noi_user','bert_user'] is invalid JSON. See jsonlint.. Be wary of using JSON and JS objects interchangeably, they are not the same thing and have subtly different syntax rules. – Liam Commented Jul 19, 2019 at 7:32
• Possible duplicate of From an array of objects, extract value of a property as array – adiga Commented Jul 19, 2019 at 7:41

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4 Answers 4

Sorted by: Reset to default 8

Use JSON.parse and then reduce to get what you want,

var s = `[{"role":"noi_user"},{"role":"bert_user"}]`

var arr = []
try {
  arr = JSON.parse(s).reduce((acc, val)=>[...acc, val.role], [])
} catch (e){
  console.log("Invalid json")
}
console.log(arr)

Is this what you are loking for ? You can map on your array and just extract the role attribute of each datum.

const jsonString = ...
const data = JSON.parse(jsonString).map(data => data.role);
console.log(JSON.stringify(data, null, 2));

JSON uses double quotes to delimit strings and field names.

So you have a JSON string like

'[{"role":"noi_user"},{"role":"bert_user"}]'

You want to convert it to an object, then extract values of "role" fields of each element, put them all into an array.

Your example json string contains an array of user objects within "role" fields. Following code takes this list, loops through each user object and puts role's of each object into a separate array roleList.

    var jsonStr = '[{"role":"noi_user"},{"role":"bert_user"}]';
    
    var userObjList = JSON.parse(jsonStr);
    var roleList = [];
    userObjList.forEach(userObj => {
        roleList.push(userObj.role);
    });
    console.log(roleList);

You could make a custom function to produce a sort of array_values in PHP but an indented and 2D level like so:

function array_values_indented (input) {
  var tmpArr = []
  for (key in input) {
    tmpArr.push(input[key]['role']);
  }
  return tmpArr
}

var object = JSON.parse('[{"role":"noi_user"},{"role":"bert_user"}]');
var result = array_values_indented(object);
console.log(result);

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