push to JSON Array if Object does not exist

I have a JSON as shown below

[

"name": "Mike",
"incentives": "23.45",
"id": "1"
,

"name": "Larsen",
"incentives": "34.78",
"id": "2"
,

"name": "Steve",
"incentives": "26.78",
"id": "3"

]


I need to push a new JSON Object into the JSON array if id not exists inside the JSON Object

tried as this way and working , any better way of doing this

$(document).ready(function()

var idsarray = ;

var test = [

"name": "Mike",
"incentives": "23.45",
"id": "1"
,

"name": "Larsen",
"incentives": "34.78",
"id": "2"
,

"name": "Steve",
"incentives": "26.78",
"id": "3"

];

for(var i=0;i<test.length;i++)

idsarray.push(test[i].id)


var newobj =
"name": "RAM",
"incentives": "56.78",
"id": "4"


var newid = newobj.id;

if(jQuery.inArray(newid, idsarray) !== -1)

test.push(newobj)


alert(test.length)

);


idsarray

3 Answers
3

Your condition is incorrect. It should be jQuery.inArray(newid, idsarray) === -1 because the operation jQuery.inArray(newid, idsarray) will return -1 if the newid is not present in idsarray. So, that is what you need, to check unique occurrence in idsarray.

jQuery.inArray(newid, idsarray) === -1

jQuery.inArray(newid, idsarray)

-1

newid

idsarray

idsarray

You can also use the indexOf() operation for the same. idsarray.indexOf(newid) === -1.

indexOf()

idsarray.indexOf(newid) === -1

OP's code

$(document).ready(function()

var idsarray = ;
var test = [
"name": "Mike",
"incentives": "23.45",
"id": "1"
,

"name": "Larsen",
"incentives": "34.78",
"id": "2"
,

"name": "Steve",
"incentives": "26.78",
"id": "3"

];

for (var i = 0; i < test.length; i++)
idsarray.push(test[i].id)


var newobj =
"name": "RAM",
"incentives": "56.78",
"id": "4"


var newid = newobj.id;
if (jQuery.inArray(newid, idsarray) === -1)
test.push(newobj)

alert(test.length)

);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

USING indexOf()

indexOf()

$(document).ready(function()

var idsarray = ;
var test = [
"name": "Mike",
"incentives": "23.45",
"id": "1"
,

"name": "Larsen",
"incentives": "34.78",
"id": "2"
,

"name": "Steve",
"incentives": "26.78",
"id": "3"

];

for (var i = 0; i < test.length; i++)
idsarray.push(test[i].id)


var newobj =
"name": "RAM",
"incentives": "56.78",
"id": "4"


var newid = newobj.id;
if (idsarray.indexOf(newobj) === -1)
test.push(newobj)

alert(test.length)

);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

inArray is slow. If you do this once, it's not the worst thing ever, but find or some on the original array would be better:

inArray

find

some

if (!test.some(o => o.id == newid))
test.push(newobj)



However, if you do this often, a much better idea is to make a set, as checking membership in a set is very very fast:

let idset = new Set();
...
if (!idset.has(newid))
test.push(newobj);
idset.add(newid);



You could also use Map (or even plain old object) to combine the two:

Map

let test = new Map();
...
if (!test.has(newid))
test.set(newobj);



You can get the array from the Map using test.values().

Map

test.values()

You can avoid the use of another array that contains the id of objects. You can use native function Array.some to check for existence and push accordingly.

array

id

var test = ["name":"Mike","incentives":"23.45","id":"1","name":"Larsen","incentives":"34.78","id":"2","name":"Steve","incentives":"26.78","id":"3"];
var newobj = "name":"RAM","incentives":"56.78","id":"4";
if(!test.some((id) => id == newobj.id)) test.push(newobj);
console.log(test);

Also, if your push operation is going to be quite frequent then looping every time will affect the performance. Instead of array of ids, you can maintain an map or set of ids as the complexity of search will be O(1).

ids

map

set

var test = ["name":"Mike","incentives":"23.45","id":"1","name":"Larsen","incentives":"34.78","id":"2","name":"Steve","incentives":"26.78","id":"3"];
var newobj = "name":"RAM","incentives":"56.78","id":"4";
var ids = test.reduce((a, id) => Object.assign(a, [id]:id), );
if(!ids[newobj.id])
test.push(newobj);
ids[newobj.id] = newobj.id;

console.log(test);

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