Javascript Object push() function

Question

I have a javascript object (I actually get the data through an ajax request):

var data = {};

I have added some stuff into it:

data[0] = { "ID": "1"; "Status": "Valid" }
data[1] = { "ID": "2"; "Status": "Invalid" }

Now I want to remove all objects with an invalid status (but keep everything the ordering same):

var tempData = {};
for ( var index in data ) {
    if ( data[index].Status == "Valid" ) {
        tempData.push( data );
    }
}
data = tempData;

In my mind, all of this should work, but I am getting an error that tempData.push is not a function. I understand why it isn't the same as an array, but what could I do otherwise?

instead of tempData.push( data ); write this tempData[index] = data. So you will not lose the order to. — Hyzyr, Dec 16 '21 at 18:27

Matt Ball · Accepted Answer · 2014-02-14T17:20:43.080

149

push() is for arrays, not objects, so use the right data structure.

var data = [];
// ...
data[0] = { "ID": "1", "Status": "Valid" };
data[1] = { "ID": "2", "Status": "Invalid" };
// ...
var tempData = [];
for ( var index=0; index<data.length; index++ ) {
    if ( data[index].Status == "Valid" ) {
        tempData.push( data );
    }
}
data = tempData;

edited Feb 14 '14 at 17:20

answered Jan 19 '12 at 12:15

Matt Ball

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+1 beat me to it. Don't forget to change the `for...in` loop, too. – Andy E Jan 19 '12 at 12:16
@MattBall my bad! I am not really that adept at SO review and stuff! :) – Shouvik Feb 14 '14 at 19:50
1

Push is for array,Is there any way to add an array to an object? – Venkat Nov 12 '15 at 04:03
1

What about associative array? – Kinnard Hockenhull Mar 30 '16 at 14:32
@KinnardHockenhull I'm sorry, I don't understand the question. Can you clarify what you're asking? – Matt Ball Mar 30 '16 at 19:34
change tempData.push( data ) to tempData.push( data[index] ) to avoid pushing the entire array. – RollingInTheDeep Jan 13 '17 at 13:23

csantana · Answer 2 · 2016-01-13T20:04:48.200

23

Objects does not support push property, but you can save it as well using the index as key,

var tempData = {};
for ( var index in data ) {
  if ( data[index].Status == "Valid" ) { 
    tempData[index] = data; 
  } 
 }
data = tempData;

I think this is easier if remove the object if its status is invalid, by doing.

for(var index in data){
  if(data[index].Status == "Invalid"){ 
    delete data[index]; 
  } 
}

And finally you don't need to create a var temp –

edited Jan 13 '16 at 20:04

answered Jan 13 '16 at 16:31

csantana

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13

Add some explanation with answer for how this answer help OP in fixing current issue – ρяσѕρєя K Jan 13 '16 at 16:53

score 6 · Answer 3 · answered Jan 19 '12 at 12:16

6

You must make var tempData = new Array();

Push is an Array function.

answered Jan 19 '12 at 12:16

Alex Dn

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12

Why `new Array()` and not `[]`? – Matt Ball Jan 19 '12 at 12:17
3

[] is an alternative (shortcut) to create new array. It can be made with [] and with new Array(). – Alex Dn Jan 19 '12 at 12:19
6

`[]` is the primary way of creating arrays, the other are alternatives and can even be overwritten. – Esailija Jan 19 '12 at 12:20
7

See http://stackoverflow.com/questions/885156/whats-wrong-with-var-x-new-array for a discussion of why `new Array()` is evil – Jonas Høgh Jan 19 '12 at 12:23
http://www.w3schools.com/js/js_obj_array.asp new Array is regular array. Where [] defined as primary? – Alex Dn Jan 19 '12 at 12:24
@Esailija I agree that not everything w3schools says is true and best practices. But I always knew that new Array() is a way to create arrays in JS and [] is a shortcut. Best practices is not a subject that OP asked about and it can be discussed for a long time. Anyway, [] is safer, new Array(100) is faster. – Alex Dn Jan 19 '12 at 12:32
@Esailija your test is not what I'm talking about...check this: http://jsperf.com/new-array-vs/2 – Alex Dn Jan 19 '12 at 12:54
@AlexDn those are not equivalent. `var a = new Array(100)` is the equivalent of `var a = []; a.length = 100;`. `new Array(100)` does not do anything but set the `length` to `100` – Esailija Jan 19 '12 at 12:56
@Esailija ok, I'm not choose the correct equivalent, but this is a modified test...still, new Array(100) is faster then []; [].length = 100; http://jsperf.com/new-array-vs/2 – Alex Dn Jan 19 '12 at 13:03
@AlexDn sure it is, and easier to write. But there are only very, very rare cases where you want `Array(x)` instead of `[]`. And `[]` is faster. – Esailija Jan 19 '12 at 13:13
@Esailija I agree, that's very rare case, but for OP question, the both versions will work. Best practices again, totally another discussion :) Why I wrote new Array and not [], just because it's the first thing that up in my mind...:) – Alex Dn Jan 19 '12 at 13:18

score 5 · Answer 4 · answered Mar 16 '16 at 19:12

Javascript programming language supports functional programming paradigm so you can do easily with these codes.

var data = [
    {"Id": "1", "Status": "Valid"},
    {"Id": "2", "Status": "Invalid"}
];
var isValid = function(data){
    return data.Status === "Valid";
};
var valids = data.filter(isValid);

score 3 · Answer 5 · answered Feb 08 '21 at 07:50

3

I hope this one might help you.

let data = [];
data[0] = { "ID": "1", "Status": "Valid" };
data[1] = { "ID": "2", "Status": "Invalid" };

let tempData = [];

tempData= data.filter((item)=>item.Status!='Invalid')

console.log(tempData)

answered Feb 08 '21 at 07:50

Prosanta Chaki

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4

RollingInTheDeep · Answer 6 · 2017-01-13T13:17:56.820

2

    tempData.push( data[index] );

I agree with the correct answer above, but.... your still not giving the index value for the data that you want to add to tempData. Without the [index] value the whole array will be added.

edited Jan 13 '17 at 13:17

answered Oct 08 '15 at 14:40

RollingInTheDeep

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Please describe how to solve the problem in detail. Thanks. – Leonid Glanz Oct 08 '15 at 15:00
This would be to correct the accepted answer from Matt Ball. As we are looping through data, we should only push data[index], not data entirely. – Jonathan Bergeron Jun 22 '16 at 14:04

Kamil Kiełczewski · Answer 7 · 2019-04-16T11:35:04.433

I assume that REALLY you get object from server and want to get object on output

Object.keys(data).map(k=> data[k].Status=='Invalid' && delete data[k])

var data = { 5: { "ID": "0", "Status": "Valid" } }; // some OBJECT from server response

data = { ...data,
  0: { "ID": "1", "Status": "Valid" },
  1: { "ID": "2", "Status": "Invalid" },
  2: { "ID": "3", "Status": "Valid" }
}

// solution 1: where output is sorted filtred array
let arr=Object.keys(data).filter(k=> data[k].Status!='Invalid').map(k=>data[k]).sort((a,b)=>+a.ID-b.ID);
  
// solution2: where output is filtered object
Object.keys(data).map(k=> data[k].Status=='Invalid' && delete data[k])
  
// show
console.log('Object',data);
console.log('Array ',arr);

score -2 · Answer 8 · answered Jan 19 '12 at 12:17

-2

Do :


var data = new Array();
var tempData = new Array();

answered Jan 19 '12 at 12:17

Sudhir Bastakoti

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Why `new Array()` and not `[]`? – Matt Ball Jan 19 '12 at 12:17
note the difference between new Array(); and new Array; You should be able to answer such questions instead of telling about alternatives.. – Jonathan Apr 08 '14 at 13:22

Javascript Object push() function

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