Develop Reference

How can I push an object into an array?

I know it's simple, but I don't get it.
I have this code:
// My object
const nieto = {
label: "Title",
value: "Ramones"
}
let nietos = [];
nietos.push(nieto.label);
nietos.push(nieto.value);
If I do this I'll get a simple array:
["Title", "Ramones"]
I need to create the following:
[{"01":"Title", "02": "Ramones"}]
How can I use push() to add the object into the nietos array?

You have to create an object. Assign the values to the object. Then push it into the array:
var nietos = [];
var obj = {};
obj["01"] = nieto.label;
obj["02"] = nieto.value;
nietos.push(obj);

Create an array of object like this:
var nietos = [];
nietos.push({"01": nieto.label, "02": nieto.value});
return nietos;
First you create the object inside of the push method and then return the newly created array.

can be done like this too.
// our object array
let data_array = [];
// our object
let my_object = {};
// load data into object
my_object.name = "stack";
my_object.age = 20;
my_object.hair_color = "red";
my_object.eye_color = "green";
// push the object to Array
data_array.push(my_object);

Using destructuring assignment (ES6)
const nieto = {label: 'title', value: 'ramones' }
const modifiedObj = {01: nieto.label, 02: nieto.value}
let array = [
{03: 'asd', 04: 'asd'},
{05: 'asd', 06: 'asd'}
]
// push the modified object to the first index of the array
array = [modifiedObj, ...array]
console.log(array)
If you'd like to push the modified object to the last index of the array just change the destructured array ...array to the front.
array = [...array, modifiedObj]

Well, ["Title", "Ramones"] is an array of strings. But [{"01":"Title", "02", "Ramones"}] is an array of object.
If you are willing to push properties or value into one object, you need to access that object and then push data into that.
Example:
nietos[indexNumber].yourProperty=yourValue; in real application:
nietos[0].02 = "Ramones";
If your array of object is already empty, make sure it has at least one object, or that object in which you are going to push data to.
Let's say, our array is myArray[], so this is now empty array, the JS engine does not know what type of data does it have, not string, not object, not number nothing. So, we are going to push an object (maybe empty object) into that array. myArray.push({}), or myArray.push({""}).
This will push an empty object into myArray which will have an index number 0, so your exact object is now myArray[0]
Then push property and value into that like this:
myArray[0].property = value;
//in your case:
myArray[0]["01"] = "value";

I'm not really sure, but you can try some like this:
var pack = function( arr ) {
var length = arr.length,
result = {},
i;
for ( i = 0; i < length; i++ ) {
result[ ( i < 10 ? '0' : '' ) + ( i + 1 ) ] = arr[ i ];
}
return result;
};
pack( [ 'one', 'two', 'three' ] ); //{01: "one", 02: "two", 03: "three"}

The below solution is more straight-forward. All you have to do is define one simple function that can "CREATE" the object from the two given items. Then simply apply this function to TWO arrays having elements for which you want to create object and save in resultArray.
var arr1 = ['01','02','03'];
var arr2 = ['item-1','item-2','item-3'];
resultArray = [];
for (var j=0; j<arr1.length; j++) {
resultArray[j] = new makeArray(arr1[j], arr2[j]);
}
function makeArray(first,second) {
this.first = first;
this.second = second;
}

This solution can be used when you have more than 2 properties in any object.
const nieto = {
label: "Title",
value: "Ramones"
}
let nietos = [];
let xyz = Object.entries(nieto)
xyz.forEach((i,j)=>{
i[0] = `${(j+1).toLocaleString("en-US", {
minimumIntegerDigits: 2,
useGrouping: false,
})}`
})
nietos.push(Object.fromEntries(xyz))

Convert Array of Javascript Objects to single simple array

I have not been able to figure out how to properly accomplish this.
I have a JS array of objects that looks like this:
[{"num":"09599","name":"KCC","id":null},{"num":"000027","name":"Johns","id":null}]
I would like to convert this into a simple, single JS array, without any of the keys, it should look like this:
[
"09599",
"KCC",
"000027",
"Johns" ]
The IDs can be dropped entirely. Any help would be really appreciated.

Simply iterate the original array, pick the interesting keys and accumulate them in another array, like this
var keys = ['num', 'name'],
result = [];
for (var i = 0; i < data.length; i += 1) {
// Get the current object to be processed
var currentObject = data[i];
for (var j = 0; j < keys.length; j += 1) {
// Get the current key to be picked from the object
var currentKey = keys[j];
// Get the value corresponding to the key from the object and
// push it to the array
result.push(currentObject[currentKey]);
}
}
console.log(result);
// [ '09599', 'KCC', '000027', 'Johns' ]
Here, data is the original array in the question. keys is an array of keys which you like to extract from the objects.
If you want to do this purely with functional programming technique, then you can use Array.prototype.reduce, Array.prototype.concat and Array.prototype.map, like this
var keys = ['num', 'name'];
console.log(data.reduce(function (result, currentObject) {
return result.concat(keys.map(function (currentKey) {
return currentObject[currentKey];
}));
}, []));
// [ '09599', 'KCC', '000027', 'Johns' ]

You can use Object.keys() and .forEach() method to iterate through your array of object, and use .map() to build your filtered array.
var array = [{"num":"09599","name":"KCC","id":null},{"num":"000027","name":"Johns","id":null}];
var filtered = array.map(function(elm){
var tmp = [];
//Loop over keys of object elm
Object.keys(elm).forEach(function(value){
//If key not equal to id
value !== 'id'
//Push element to temporary array
? tmp.push(elm[value])
//otherwise, do nothing
: false
});
//return our array
return tmp;
});
//Flat our filtered array
filtered = [].concat.apply([], filtered);
console.log(filtered);
//["09599", "KCC", "000027", "Johns"]

How about using map :
var data = [
{"num":"09599","name":"KCC","id":null}
{"num":"000027","name":"Johns","id":null}
];
var result = data.map(function(obj) {
return [
obj.num,
obj.name,
obj.id
];
});

Returning only certain properties from an array of objects in Javascript [duplicate]

This question already has answers here:
From an array of objects, extract value of a property as array
(24 answers)
Closed 8 years ago.
If I have an object such that
var object = function(key,text)
{
this.key = key;
this.text = text;
}
And create an array of these objects
var objArray = [];
objArray[0] = new object('key1','blank');
objArray[1] = new object('key2','exampletext');
objArray[2] = new object('key3','moretext');
is there a way that I can retrieve only one of the properties of all of the objects in the array? For example:
var keyArray = objArray["key"];
The above example doesn't return set keyArray to anything, but I was hoping it would be set to something like this:
keyArray = [
'key1',
'key2',
'key3']
Does anyone know of a way to do this without iterating through the objArray and manually copying each key property to the key array?

This is easily done with the Array.prototype.map() function:
var keyArray = objArray.map(function(item) { return item["key"]; });
If you are going to do this often, you could write a function that abstracts away the map:
function pluck(array, key) {
return array.map(function(item) { return item[key]; });
}
In fact, the Underscore library has a built-in function called pluck that does exactly that.

var object = function(key,text) {
this.key = key;
this.text = text;
}
var objArray = [];
objArray[0] = new object('key1','blank');
objArray[1] = new object('key2','exampletext');
objArray[2] = new object('key3','moretext');
var keys = objArray.map(function(o,i) {
return o.key;
});
console.log(keys); // ["key1", "key2", "key3"]
JS Bin Example
http://jsbin.com/vamey/1/edit
Note that older browsers may not support map but you can easily do this with a for loop:
var keys = [];
for (var i = 0; i < objArray.length; i++) {
keys.push(objArray[i].key);
}
JS Bin Example
http://jsbin.com/redis/1/edit

You would want to do something like this:
objArray.map(function (obj) { return obj.key; });
Here is a JSFiddle to demo: http://jsfiddle.net/Q7Cb3/
If you need older browser support, you can use your own method:
JSFiddle demo: http://jsfiddle.net/Q7Cb3/1/
function map (arr, func) {
var i = arr.length;
arr = arr.slice();
while (i--) arr[i] = func(arr[i]);
return arr;
}

Well something has to iterate through the elements of the array. You can use .map() to make it look nice:
var keys = objArray.map(function(o) { return o.key; });
You could make a function to generate a function to retrieve a particular key:
function plucker(prop) {
return function(o) {
return o[prop];
};
}
Then:
var keys = objArray.map(plucker("key"));

Really "objArray" is an array that have 3 objects inside, if you want list of keys, you can try this:
var keys = [];
for(a in objArray) {
keys.push(objArray[a].key);
}
You have in var keys, the three keys.
Hope that helps! :)

How to convert Object into array in jquery/javascript

I want to convert an object with specific properties into array of string containing properties values. For an instance take Object Employee with below properties with values
Employee.Name='XYZ'
Employee.ID=123
Employee.Address='ABC'
I want this all to be in array as
var arr=['XYZ',123,'ABC']
How to iterate over the properties. Is this possible? Please assist here.

Use $.map()
var arr = $.map(Employee, function(value, key){
return value
})
Demo: Fiddle
Note: The order of loop is not dependable, so the order of values in the array may not be always same
Another way to handle it is to use a fixed array of keys so that the output array will have a predefined sequence
var keys = ['Name', 'ID', 'Address'];
var Employee = {};
Employee.Name = 'XYZ'
Employee.ID = 123
Employee.Address = 'ABC'
var arr = $.map(keys, function (key, idx) {
return Employee[key]
})
console.log(arr)
Demo: Fiddle

Loop through the object like this
var arr = [];
for (var key in Employee) {
arr.push(Employee[key]);
}
Note: Order is not defined in this case

You can loop through each property and add it's value to the array:
var arr = [];
for (var prop in Employee) {
if (Employee.hasOwnProperty(prop)) {
arr.push(Employee[prop]);
}
}
Example - http://jsfiddle.net/infernalbadger/2PHpZ/
Or using jQuery:
var arr = $.map(Employee, function(propValue) {
return propValue;
});
Example - http://jsfiddle.net/infernalbadger/2PHpZ/1/

var myArray=[];
for (var key in Employee) {
if (Employee.hasOwnProperty(key)) {
myArray.push(Employee[key]));
}
}

var Employee = {};
Employee.Name='XYZ';
Employee.ID=123;
Employee.Address='ABC';
var empArray =[];
$.each(Employee,function(item){
empArray.push(item);
});
console.log(empArray);
fiddle

JavaScript since 1.7. Reference to JavaScript language advanced Tips & Tricks.
var arr = [Employee.Name,Employee.ID,Employee.Address];

Declaring array of objects

I have a variable which is an array and I want every element of the array to act as an object by default. To achieve this, I can do something like this in my code.
var sample = new Array();
sample[0] = new Object();
sample[1] = new Object();
This works fine, but I don't want to mention any index number. I want all elements of my array to be an object. How do I declare or initialize it?
var sample = new Array();
sample[] = new Object();
I tried the above code but it doesn't work. How do I initialize an array of objects without using an index number?

Use array.push() to add an item to the end of the array.
var sample = new Array();
sample.push(new Object());
To do this n times use a for loop.
var n = 100;
var sample = new Array();
for (var i = 0; i < n; i++)
sample.push(new Object());
Note that you can also substitute new Array() with [] and new Object() with {} so it becomes:
var n = 100;
var sample = [];
for (var i = 0; i < n; i++)
sample.push({});

Depending on what you mean by declaring, you can try using object literals in an array literal:
var sample = [{}, {}, {} /*, ... */];
EDIT: If your goal is an array whose undefined items are empty object literals by default, you can write a small utility function:
function getDefaultObjectAt(array, index)
{
return array[index] = array[index] || {};
}
Then use it like this:
var sample = [];
var obj = getDefaultObjectAt(sample, 0); // {} returned and stored at index 0.
Or even:
getDefaultObjectAt(sample, 1).prop = "val"; // { prop: "val" } stored at index 1.
Of course, direct assignment to the return value of getDefaultObjectAt() will not work, so you cannot write:
getDefaultObjectAt(sample, 2) = { prop: "val" };

You can use fill().
let arr = new Array(5).fill('lol');
let arr2 = new Array(5).fill({ test: 'a' });
// or if you want different objects
let arr3 = new Array(5).fill().map((_, i) => ({ id: i }));
Will create an array of 5 items. Then you can use forEach for example.
arr.forEach(str => console.log(str));
Note that when doing new Array(5) it's just an object with length 5 and the array is empty. When you use fill() you fill each individual spot with whatever you want.

After seeing how you responded in the comments. It seems like it would be best to use push as others have suggested. This way you don't need to know the indices, but you can still add to the array.
var arr = [];
function funcInJsFile() {
// Do Stuff
var obj = {x: 54, y: 10};
arr.push(obj);
}
In this case, every time you use that function, it will push a new object into the array.

You don't really need to create blank Objects ever. You can't do anything with them. Just add your working objects to the sample as needed. Use push as Daniel Imms suggested, and use literals as Frédéric Hamidi suggested. You seem to want to program Javascript like C.
var samples = []; /* If you have no data to put in yet. */
/* Later, probably in a callback method with computed data */
/* replacing the constants. */
samples.push(new Sample(1, 2, 3)); /* Assuming Sample is an object. */
/* or */
samples.push({id: 23, chemical: "NO2", ppm: 1.4}); /* Object literal. */
I believe using new Array(10) creates an array with 10 undefined elements.

You can instantiate an array of "object type" in one line like this (just replace new Object() with your object):
var elements = 1000;
var MyArray = Array.apply(null, Array(elements)).map(function () { return new Object(); });

Well array.length should do the trick or not? something like, i mean you don't need to know the index range if you just read it..
var arrayContainingObjects = [];
for (var i = 0; i < arrayContainingYourItems.length; i++){
arrayContainingObjects.push {(property: arrayContainingYourItems[i])};
}
Maybe i didn't understand your Question correctly, but you should be able to get the length of your Array this way and transforming them into objects. Daniel kind of gave the same answer to be honest. You could just save your array-length in to his variable and it would be done.
IF and this should not happen in my opinion you can't get your Array-length. As you said w/o getting the index number you could do it like this:
var arrayContainingObjects = [];
for (;;){
try{
arrayContainingObjects.push {(property: arrayContainingYourItems[i])};
}
}
catch(err){
break;
}
It is the not-nice version of the one above but the loop would execute until you "run" out of the index range.

//making array of book object
var books = [];
var new_book = {id: "book1", name: "twilight", category: "Movies", price: 10};
books.push(new_book);
new_book = {id: "book2", name: "The_call", category: "Movies", price: 17};
books.push(new_book);
console.log(books[0].id);
console.log(books[0].name);
console.log(books[0].category);
console.log(books[0].price);
// also we have array of albums
var albums = []
var new_album = {id: "album1", name: "Ahla w Ahla", category: "Music", price: 15};
albums.push(new_album);
new_album = {id: "album2", name: "El-leila", category: "Music", price: 29};
albums.push(new_album);
//Now, content [0] contains all books & content[1] contains all albums
var content = [];
content.push(books);
content.push(albums);
var my_books = content[0];
var my_albums = content[1];
console.log(my_books[0].name);
console.log(my_books[1].name);
console.log(my_albums[0].name);
console.log(my_albums[1].name);
This Example Works with me.
Snapshot for the Output on Browser Console

Try this-
var arr = [];
arr.push({});

const sample = [];
list.forEach(element => {
const item = {} as { name: string, description: string };
item.name= element.name;
item.description= element.description;
sample.push(item);
});
return sample;
Anyone try this.. and suggest something.

Use array.push() to add an item to the end of the array.
var sample = new Array();
sample.push(new Object());
you can use it
var x = 100;
var sample = [];
for(let i=0; i<x ;i++){
sample.push({})
OR
sample.push(new Object())
}

Using forEach we can store data in case we have already data we want to do some business login on data.
var sample = new Array();
var x = 10;
var sample = [1,2,3,4,5,6,7,8,9];
var data = [];
sample.forEach(function(item){
data.push(item);
})
document.write(data);
Example by using simple for loop
var data = [];
for(var i = 0 ; i < 10 ; i++){
data.push(i);
}
document.write(data);

If you want all elements inside an array to be objects, you can use of JavaScript Proxy to apply a validation on objects before you insert them in an array. It's quite simple,
const arr = new Proxy(new Array(), {
set(target, key, value) {
if ((value !== null && typeof value === 'object') || key === 'length') {
return Reflect.set(...arguments);
} else {
throw new Error('Only objects are allowed');
}
}
});
Now if you try to do something like this:
arr[0] = 'Hello World'; // Error
It will throw an error. However if you insert an object, it will be allowed:
arr[0] = {}; // Allowed
For more details on Proxies please refer to this link:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy
If you are looking for a polyfill implementation you can checkout this link:
https://github.com/GoogleChrome/proxy-polyfill

The below code from my project maybe it good for you
reCalculateDetailSummary(updateMode: boolean) {
var summaryList: any = [];
var list: any;
if (updateMode) { list = this.state.pageParams.data.chargeDefinitionList }
else {
list = this.state.chargeDefinitionList;
}
list.forEach((item: any) => {
if (summaryList == null || summaryList.length == 0) {
var obj = {
chargeClassification: item.classfication,
totalChargeAmount: item.chargeAmount
};
summaryList.push(obj);
} else {
if (summaryList.find((x: any) => x.chargeClassification == item.classfication)) {
summaryList.find((x: any) => x.chargeClassification == item.classfication)
.totalChargeAmount += item.chargeAmount;
}
}
});
if (summaryList != null && summaryList.length != 0) {
summaryList.push({
chargeClassification: 'Total',
totalChargeAmount: summaryList.reduce((a: any, b: any) => a + b).totalChargeAmount
})
}
this.setState({ detailSummaryList: summaryList });
}

var ArrayofObjects = [{}]; //An empty array of objects.