Converting JSON value into JavaScript array

Question

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 comma when in alert but the comma missing as i display them in the text field and it becomes a long string like noi_userbert_user

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

as an FYI the quote type (' and " are identical in JS) are irrelevant — Liam
– 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.com. Be wary of using JSON and JS objects interchangeably, they are not the same thing and have subtly different syntax rules. — Liam
– Liam, Commented Jul 19, 2019 at 7:32
Possible duplicate of From an array of objects, extract value of a property as array — adiga
– adiga, Commented Jul 19, 2019 at 7:41

Anurag Awasthi · Accepted Answer · 2019-07-19 07:28:48Z

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)

answered Jul 19, 2019 at 7:28

Anurag Awasthi

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3 Comments

Abner Stan. Over a year ago

but brother, do you know why if i set my text field with the array value, the comma and the [bracket] went missing. I am still getting a long string without any delimited thing.

Anurag Awasthi Over a year ago

When you set array value to input field value, js will convert array to string by calling it's toString method, which will join the array value to make a string.

Abner Stan. Over a year ago

Thats right. Thanks brother. and I am using toString to convert the array before displaying it into the field control and all went good.

adz5A · Accepted Answer · 2019-07-19 07:27:14Z

2

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.

answered Jul 19, 2019 at 7:27

adz5A

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Comments

Safa Kadir · Accepted Answer · 2019-07-19 07:36:59Z

1

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);

answered Jul 19, 2019 at 7:36

Safa Kadir

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Comments

Abhay Maurya · Accepted Answer · 2019-09-26 06:36:39Z

1

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);

edited Sep 26, 2019 at 6:36

answered Jul 19, 2019 at 7:37

Abhay Maurya

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