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JavaScript create or update key in JSON object [duplicate]

This question already has answers here:
JavaScript - cannot set property of undefined
(8 answers)
Closed 1 year ago.
I want to create JSON object using pure JavaScript as below:
{
"0": {
"0": {
"key1": 1,
"key2": 2
},
"1": {
"key1": 1,
"key2": 2
}
}
"1": {
"0": {
"key1": 1,
"key2": 2
}
}
}
But when I try below code I get error for undefined:
var myJosnObj = {};
myJosnObj["0"]["0"] = {"key1": 1,"key2": 2};
I am getting error:
Error: myJosnObj[0] is undefined
I want to either create or update the existing key in the json document.

const myJosnObj = {};
myJosnObj["0"] = {}
myJosnObj["0"]["0"] = {"key1": 1,"key2": 2};
You need to define myJosnObj["0"]

you can directly do :
const myJosnObj =
{ "0":
{ "0": { "key1": 1, "key2": 2}
, "1": { "key1": 1, "key2": 2}
}
, "1":
{ "0": { "key1": 1, "key2": 2}
}
}

Order object keys according to key list in JavaScript [duplicate]

This question already has answers here:
Sort JavaScript object by key
(37 answers)
Closed 3 years ago.
I have a list for order of field to display
field_order = ["name", "age", "birthday"]
I got a list of objects like this
_data_set = {
"age": 23,
"birthday": "2000-12-12"
"name": "A"
}
I need to order Object keys according to field_order.
Expected result:
_data_set = {
"name": "A",
"age": 23,
"birthday": "2000-12-12"
}

Key order is chronological in JavaScript since ES2015, so we can order like so:
There's a nice article on this: property-traversal-order-es6
field_order = ["name", "age", "birthday"]
_data_set = {
"age": 23,
"birthday": "2000-12-12",
"name": "A"
};
let result = field_order.reduce( (obj, v) => {
obj[v] = _data_set[v];
return obj;
}, {});
console.log(result);

At first you need to sort and then just create an object with desired order of keys:
let field_order = ["name", "age", "birthday"];
let _data_set = {
"age": 23,
"birthday": "2000-12-12",
"name": "A"
}
let order = {name: -1, age: 0, birthday: 1};
const result = {};
Object.keys(_data_set)
.sort((a,b)=> order[a] - order[b])
.forEach(key=> result[key] = _data_set[key]);
console.log(result);

You could use the following:
let new_data_set = {};
for(let item of field_order) {
new_data_set[item] = _data_set[item];
}

How can i get my required data from array of objects using javascript? [closed]

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Closed 4 years ago.
Improve this question
I have array of objects like this
var a = [
{'time' : 1539664755070,'T-1': 23 },
{'time' : 1539665095442,'H-1': 24 },
{'time' : 1539666489560,'T-1': 42 },
{'time' : 1539665095442,'H-1': 27 },
{'time': 1539671682230,'H-1': 40.45,'T-2': 33},
{'time': 1539671682230,'T-2': 30.45,'T-1': 65},
{'time': 1539671682230,'T-2': 42.45,'H-1': 11},
{'time': 1539671682230,'T-1': 50.45,'T-2': 85}
];
I want to have data like this
data : {
'T-1' : [23,42,50.45],
'T-2' : [33,30.45,85],
'H-1' : [24,27,40.45,11]
}
How can i get this data from given data?

Here is a solution, if something is not clear, please lemme know:
const result = {};
a.forEach(object => {
// Loop on each entry in the original array
Object.entries(object).forEach(([key,value]) => {
// Loop through each entry of one entry of the original array
// (ex 'T-1', 'T-2')
if(key !== 'time') {
// It's a key that I'm interested in, so do logic
if(!result[key]) {
// If the key (example 'T-1') haven't been encountered yet,
// initialize it's entry in the result with an empty array
result[key] = [];
}
result[key].push(value);
}
});
});

Best use case for using Map instead of Key,Value arrays. Simplifies lot of things.

You can use array#reduce with Object.values() to create a hash of your key and add the values corresponding to it. Then using Object.assign() and spread syntax you can create the final object.
let data = [ {'time' : 1539664755070,'T-1': 23 }, {'time' : 1539665095442,'H-1': 24 }, {'time' : 1539666489560,'T-1': 42 }, {'time' : 1539665095442,'H-1': 27 }, {'time': 1539671682230,'H-1': 40.45,'T-2': 33}, {'time': 1539671682230,'T-2': 30.45,'T-1': 65},{'time': 1539671682230,'T-2': 42.45,'H-1': 11}, {'time': 1539671682230,'T-1': 50.45,'T-2': 85} ],
result = Object.assign({}, ...Object.values(data.reduce((r, o) => {
let keys = Object.keys(o).filter(k => k !== 'time');
keys.forEach(key => {
r[key] = r[key] || {[key] : []};
r[key][key].push(o[key]);
});
return r;
},{})));
console.log(result);

const data = a.reduce((acc, row) => {
// Loop over keys of each row.
Object.keys(row)
// Filter out the "time" keys.
.filter((key) => key !== 'time')
// Collect the values by key, storing them in the accumulator.
.forEach((key) => {
if (typeof acc[key] === 'undefined') {
acc[key] = []
}
acc[key].push(row[key])
})
return acc
}, {})

How order a JSON alphabetically in javascript, like this? [closed]

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Closed 5 years ago.
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I can ordering a-z using the .sort() method in javascript, but I would get a JSON like this: (With a "A-Z" index containing the result)
data: {
"A": [
{
"name": "Anh Tuan Nguyen",
"age": 28
},
{
"name": "An Nguyen",
"age": 20
},
],
"Z": [
{
"name": "Zue Dang",
"age": 22
},
{
"name": "Zoom Jane",
"age": 30
},
]
}

var names = [{name:"a1"},{name:"a2"},{name:"b1"},{name:"b2"}.....];
var data = {};
for (var i = 0; i < names.length; i++) {
var n = names[i].name.subStr(0,1);
if (data[n] == null)
data[n] = [];
data[n].push(names[i]);
}

There is no way to sort a JSON data structure, however, we can do it by using the following process:
Get your data keys with Object.keys(myResults.data)
Sort you keys
Create a reduce function to transform your ordered keys into an ordered object
The snippet is here, I hope it helps:
var myResults = {
data: {
C: [
{
"name": "Kevin Doe",
"age": 22
}
],
A: [
{
"name": "Alex Doe",
"age": 31,
}
],
B: [
{
"name": "Boris Doe",
"age": 22
},
{
"name": "Birdo Doe",
"age": 30
},
]
}
};
var originalData = myResults.data;
// 1. get the keys
var dataKeys = Object.keys(originalData);
// 2. sort the keys
var sortedKeys = dataKeys.sort();
// 3. create the object again
var orderedData = sortedKeys.reduce(function(result, key) {
return Object.assign(
{},
result,
{ [key]: myResults.data[key] }
);
}, {});
document.getElementById('original').innerHTML = JSON.stringify(originalData);
document.getElementById('sorted').innerHTML = JSON.stringify(orderedData);
h3 {
margin: 0;
}
code {
display: block;
margin-bottom: 15px;
padding: 10px;
background-color: #f9f9f9;
}
<h3>Original Data</h3>
<code id="original"></code>
<h3>Ordered Data</h3>
<code id="sorted"></code>

JavaScript objects are not ordered. If you want to iterate over an object's properties, you can sort the keys and then retrieve your values:
const result = {
data: {
Z: [],
F: [],
A: [],
D: []
}
};
Object
.keys(result.data)
.sort()
.map(key => console.log(key, result.data[key]));

UPDATE:
Exist a JavaScript library that make It possible: Lodash Utilities (https://lodash.com/docs/4.17.4). Contain methods for .sort() JSON (no Arrays) and a method to obtain the JSON for I asked in this question. I only did this:
//First, order my JSON alphabetically with _.sortBy method (I can even order by a nested property in my JSON)
var order = _.sortBy(require('./names'), function (el) { return el.name });
//Second, I group my order result by the first letter of my property 'name' in my JSON
var list = _.groupBy(order, (b) => b.name[0].toUpperCase());
This is my input:
[
{"name":"Mark"},
{"name":"Jul"},
{"name":"Alicia"},
]
This is my output:
[
"A": [
{
"name": "Alicia"
}
],
"J": [
{
"name": "Jul"
},
],
"M": [
{
"name": "Mark"
},
]
I hope this help to somebody!

how to edit JSON value using Javascript or Jquery [duplicate]

This question already has answers here:
How can I access and process nested objects, arrays, or JSON?
(31 answers)
Closed 7 years ago.
i want have a value for a specific key may be nested value also like change value of key1 to value100 or key11 to value111.
{
"key1": "value1",
"key2": "value2",
"key3": "value3",
"map1" : {"key4":"value4",
"key5":"value5",
"key6":"value6",
"map2" :
{
"key7":"value7",
"key8":"value8",
"key9":"value9",
"map3" :
{
"key10":"value10",
"key11":"value11",
"key12":"value12"
},
"map4" :
{
"key13":"value13",
"key14":"value14",
"key15":"value15"
}
}
}
}
how to achieve this using javascript or jquery. please help me to find out the issue.

If you stored that in a variable like
var object = { *your JSON here*}
you can access it like:
object.key1
to obtain the value of your key1
If you want to get those in map2, it would be:
object.map2.key7
e.g.
If you want to change values, just do
object.key = *value*;

You can just hold your json on javascript object and edit it.
var _j ={
"key1": "value1",
"key2": "value2",
"key3": "value3",
"map1" : {"key4":"value4",
"key5":"value5",
"key6":"value6",
"map2" :
{
"key7":"value7",
"key8":"value8",
"key9":"value9",
"map3" :
{
"key10":"value10",
"key11":"value11",
"key12":"value12"
},
"map4" :
{
"key13":"value13",
"key14":"value14",
"key15":"value15"
}
}
}
};
_j.key1 = "New Key1";
$('div').html(JSON.stringify(_j));
Here is working JS Fiddle