How to get all key in JSON object (javascript)

Question

{"document":
  {"people":[
    {"name":["Harry Potter"],"age":["18"],"gender":["Male"]},
    {"name":["hermione granger"],"age":["18"],"gender":["Female"]},
  ]}
}

From this JSON example, I would like to get the keys such as name, age, gender for each people.

How to do this?

Your JSON structure is incorrect. Name, age, and gender should be single properties, not lists. It should be {"name": "Harry Potter", "age":"18", "gender":"Male"} (no square brackets). — nbrooks
– nbrooks, Commented Nov 13, 2014 at 5:50
This has nothing to do with JSON, which is just a text format. — Heretic Monkey
– Heretic Monkey, Commented Jan 17, 2020 at 22:43

Lars Flieger · Accepted Answer · 2023-10-02 08:51:04Z

93

I use Object.keys which is built into JavaScript Object, it will return an array of keys from given object MDN Reference

const person = {
  name: "Jeeva",
  age: "22",
  gender: "Male"
}
console.log(Object.keys(person))

edited Oct 2, 2023 at 8:51

Lars Flieger

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answered Sep 1, 2017 at 23:43

Jeeva

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3 Comments

Mikkel Over a year ago

This isn't the correct solution to what was asked. All you did was simplify the problem and solve that, which won't be of any help

Jeeva Over a year ago

Oh sorry, I am new to answering questions. I will keep that in mind next time

acidjunk Over a year ago

FWIW: the accepted solution also doesn't answer the question.

Rahul G Nair · Accepted Answer · 2014-11-14 06:03:37Z

52

Try this

var s = {name: "raul", age: "22", gender: "Male"}
   var keys = [];
   for(var k in s) keys.push(k);

Here keys array will return your keys ["name", "age", "gender"]

answered Nov 14, 2014 at 6:03

Rahul G Nair

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3 Comments

Shubhendu Vaid Over a year ago

Can we have a generic solution. Like working for this:

var object3 = {     parent1: 42,     parent2: [13, 12, { 'child1': 222 }],     parent3: {         child1: 44,         child2: "ok",         child3: [44, 45, 47, 48]     },     parent4: {         child1: 444     } };

Nisrine Bou Ghannam Over a year ago

how can we return all keys in nested objects and arrays? like getting all keys from "data":{ "user":{ "id": 1, "name": "xyz" }, "address":[ "street":"xyz", "location: "xxx"] }

Todd Brannon Over a year ago

@NisrineBouGhannam did you ever find a solution for this question - I am wondering the same thing.

BatScream · Accepted Answer · 2014-11-14 13:34:53Z

18

var input = {"document":
  {"people":[
    {"name":["Harry Potter"],"age":["18"],"gender":["Male"]},
    {"name":["hermione granger"],"age":["18"],"gender":["Female"]},
  ]}
}

var keys = [];
for(var i = 0;i<input.document.people.length;i++)
{
    Object.keys(input.document.people[i]).forEach(function(key){
        if(keys.indexOf(key) == -1)
        {
            keys.push(key);
        }
    });
}
console.log(keys);

edited Nov 14, 2014 at 13:34

answered Nov 13, 2014 at 5:35

BatScream

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6 Comments

vp_arth Over a year ago

Object.keys called on non-object can be here, if people is empty array

vp_arth Over a year ago

I think your first version was a best answer, need only check array isn't empty. Current version is too complicated :)

nbrooks Over a year ago

This is a good solution, and prevents the same keys from being added more than once

BatScream Over a year ago

@vp_arth Actually, that would work only for the first item in the array, say if the second or third object have some extra properties like "address", it would have failed.

vp_arth Over a year ago

It is other task with some other conditions, may be need to get only common fields of all entities.

|

Tuucan · Accepted Answer · 2018-07-09 09:04:06Z

8

ES6 of the day here;

const json_getAllKeys = data => (
  data.reduce((keys, obj) => (
    keys.concat(Object.keys(obj).filter(key => (
      keys.indexOf(key) === -1))
    )
  ), [])
)

And yes it can be written in very long one line;

const json_getAllKeys = data => data.reduce((keys, obj) => keys.concat(Object.keys(obj).filter(key => keys.indexOf(key) === -1)), [])

EDIT: Returns all first order keys if the input is of type array of objects

edited Jul 9, 2018 at 9:04

answered Jul 18, 2017 at 13:59

Tuucan

931 silver badge7 bronze badges

Comments

Brian T.A. · Accepted Answer · 2022-03-14 16:11:37Z

This function should return an array of ALL the keys (i.e. the key names) in a JSON object including nested key/value pairs.

function get_all_json_keys(json_object, ret_array = []) {
    for (json_key in json_object) {
        if (typeof(json_object[json_key]) === 'object' && !Array.isArray(json_object[json_key])) {
            ret_array.push(json_key);
            get_all_json_keys(json_object[json_key], ret_array);
        } else if (Array.isArray(json_object[json_key])) {
            ret_array.push(json_key);
            first_element = json_object[json_key][0];
            if (typeof(first_element) === 'object') {
                get_all_json_keys(first_element, ret_array);
            }
        } else {
            ret_array.push(json_key);
        }
    }

    return ret_array
}

Using this function on the OP's original object

const op_object =
{
    "document":{
       "people":[
          {
             "name":[
                "Harry Potter"
             ],
             "age":[
                "18"
             ],
             "gender":[
                "Male"
             ]
          },
          {
             "name":[
                "hermione granger"
             ],
             "age":[
                "18"
             ],
             "gender":[
                "Female"
             ]
          }
       ]
    }
 }

var all_keys = [];

function get_all_json_keys(json_object, ret_array = []) {
    for (json_key in json_object) {
        if (typeof(json_object[json_key]) === 'object' && !Array.isArray(json_object[json_key])) {
            ret_array.push(json_key);
            get_all_json_keys(json_object[json_key], ret_array);
        } else if (Array.isArray(json_object[json_key])) {
            ret_array.push(json_key);
            first_element = json_object[json_key][0];
            if (typeof(first_element) === 'object') {
                get_all_json_keys(first_element, ret_array);
            }
        } else {
            ret_array.push(json_key);
        }
    }

    return ret_array
}

get_all_json_keys(op_object, all_keys);

console.log(all_keys);

should yield

[ 'document', 'people', 'name', 'age', 'gender' ]

Note: This will return a unique list of all key names.

Robert · Accepted Answer · 2021-02-06 06:40:01Z

3

var jsonData = { Name: "Ricardo Vasquez", age: "46", Email: "[email protected]" };

for (x in jsonData) {   
  console.log(x +" => "+ jsonData[x]);  
  alert(x +" => "+  jsonData[x]);  
  }

edited Feb 6, 2021 at 6:40

Robert

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answered Feb 5, 2021 at 18:07

RICARDO VASQUEZ

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1 Comment

Adrian Mole Over a year ago

While this code may solve the question, including an explanation of how and why this solves the problem would really help to improve the quality of your post, and probably result in more up-votes. Remember that you are answering the question for readers in the future, not just the person asking now. Please edit your answer to add explanations and give an indication of what limitations and assumptions apply.

AllanRibas · Accepted Answer · 2021-04-06 22:43:56Z

0

We must "parse" our jsonObject

 console.log('{"key0":"value0", "key1":"value1"}'); 
    var jsonObject = JSON.parse('{"key0":"value0", "key1":"value1"}')
    Object.keys(jsonObject).forEach(key => { 
        console.log(jsonObject[key]); //values 
        console.log(key); //keys 
    })

edited Apr 6, 2021 at 22:43

answered Apr 6, 2021 at 22:03

AllanRibas

1,22214 silver badges19 bronze badges

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