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Combining two arrays into an object

I have two arrays one with label date i.e [Date, Date, Date ...] and
the other with the actual date data i.e [2021-11-26, 2021-11-25, ...].
I want to combine these two arrays such that I get array of objects such as [ { Date: 2021-11-26}, {Date:2021-11-25}, {..}, ...].
I have tried these two methods
obj = {};
for (var i = 0, l = date_label.length; i < l; i += 1) {
obj[date_label[i]] = data_date[i]
}
console.log(obj);
and
_.zipObject(date_label, data_date);
However it only ends up giving me the last date of my data set, in an object data structure ie { Date: 1999-11-24}

The keys inside an object / associative array are unique. Your obj is such a thing. If you turn it into a regular array and push new objects into it, it will work.
const obj = [];
for (let i = 0, l = date_label.length; i < l; i++) {
obj.push({[date_label[i]]: data_date[i]})
}
console.log(obj);
You should probably assert that both your arrays have the same length.

The issues you are facing is that your date_label are the same and the loop are replacing the dates on the same label, again and again, you just need to change the label name and give unique to each one or you change them into the loop as well like this (obj[date_label[i] + str(i)] = data_date[i]).
date_label = ['date1', 'date2', 'date3', .....]
obj = {};
for (var i = 0, l = date_label.length; i < l; i += 1) {
obj[date_label[i]] = data_date[i]
}
console.log(obj);

obj is of type array not object.
data_date needs to be in string format.
for(var i= 0; i<data_date.length-1;i++) {
obj.push({"Date":date_date[i]}) }

with array reduce
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce
var myFinalArray = data_date.reduce(
(previousValue, currentValue, currentIndex, array) => ({
currentValue: date_label[currentIndex]
}), {});

Hello AshleyCrasto,
Welcome to Stackoverflow.
Sol : Well, the other members have given solution on how to achieve the desired result. I will emphasize on why you are getting the single object.
it only ends up giving me the last date of my data set, in an object data structure ie { Date: 1999-11-24}
You need to understand how references work in JavaScript. Heres the catch,
As the values in date_label are all same
[Date, Date, Date ...]
When you use,
obj[date_label[i]] = data_date[i]
Everytime, it get executed the same key value will be keep updating instead of creating new key and new value. Because the same values holds same reference.
So, first time {"date" : "somevalue"} will be there, then
second time {"date" : "somevalue2"}, the value of key "date" will be updated
with new value. This is due to same key.
Therefore, you need to take of this thing. For your better understanding here is my code: (same as others but elaborately)
const date_label = ["date","date"]
const data_date = [2021-11-26, 2021-11-25]
function returnObj(label, value){
//this will return a new object with provided label and value.
const Obj = {};
Obj[label] = value
return Obj
}
let listOfObjects = []
for(let i=0 ; i< date_label.length ; i++){
//new object will be added to list.
const obj = returnObj(date_label[i],data_date[i])
listOfObjects.push(obj)
}
console.log(listOfObjects)

How to remove double quotes from json array in javascript

I have a array :
Var array=[{"name":"May","data1":"1121.0"}]
I want to change it to :
Var array= [{"name":"May","data1":1121.0}]

You can simply check using Number.isNaN with an attempted cast to a number using the + operator. If it returns true then do nothing. If it's false then change the value of the parameter to a cast number.
var array=[{"name":"May","data1":"1121.0"}];
array.forEach(data => {
for(let key in data) Number.isNaN(+data[key]) || (data[key] = +data[key])
});
console.log(array);

Looks like this has been answered before here
I'll summarize;
for(var i = 0; i < objects.length; i++){
var obj = objects[i];
for(var prop in obj){
if(obj.hasOwnProperty(prop) && obj[prop] !== null && !isNaN(obj[prop])){
obj[prop] = +obj[prop];
}
}
}
console.log(JSON.stringify(objects, null, 2));
This does have a bug where 0 becomes null.

You want to convert the value mapped to the "data1" key to be a number instead of a string.
There are many ways to accomplish this in JavaScript, but the best way to do so would be to use Number.parseFloat like so:
var array = [{"name":"May","data1":"1121.0"}];
array[0]["data1"] = Number.parseFloat(array[0]["data1"]);
console.log(array[0]["data1"]); // 1121
If you need to perform this action with multiple objects inside of array, you could do
var array = [{"name":"May","data1":"1121.0"}, {"name":"May","data1":"1532.0"}, etc.] // Note that this is not valid JavaScript
array.map(obj => {obj["data1"] = Number.parseFloat(obj["data1"]); return obj;});

If I understood well, you only want to convert the value of data1, from "1121.0" to 1121.0, in other words from string to number.
To convert only that key (data1), you only need this:
array[0].data1 = parseFloat(array[0].data1)
If that's not what you want, please explain better your question

how to associate key to each individual array and make them key value pair

i have array like this
[["apple","banana"],["monkey"]];
how can i associate key to them like,
[{"fruit":["apple","banana"],"wild":["monkey"]}]
is this possible?
i'm trying something like this
var arr = [["apple","banana"],["monkey"]];
var newArray = [];
for(var i=0;i<arr.length;i++){
newArray["fruit"] = arr[i] //further code i don't know
}
help me th

While you can do that, like this:
var array = [["apple","banana"],["monkey"]];
var update = [
{fruit: array[0], wild: array[1]}
];
console.log(update);
...frankly it seems unlikely that's really want you want.

Very simply you can assign a new name simply
var array = [["apple","banana"],["monkey"]];
var names = ["fruits", "wild"]
var modified = [{names[0]: array[0], names[1]: array[1]}];
If you have a lot of values just use a for loop to iterate and assign value to it.

Find duplicate object values in an array and merge them - JAVASCRIPT

I have an array of objects which contain certain duplicate properties: Following is the array sample:
var jsonData = [{x:12, machine1: 7}, {x:15, machine2:7},{x:12, machine2: 8}];
So what i need is to merge the objects with same values of x like the following array:
var jsonData = [{x:12, machine1:7, machine2:8}, {x:15, machine2:7}]

I like the lodash library.
https://lodash.com/docs#groupBy
_.groupBy(jsonData, 'x') produces:
12: [ {x=12, machine1=7}, {x=12, machine2=8} ],
15: [ {x=15, machine2=7} ]
your desired result is achieved like this:
var jsonData = [{x:12, machine1: 7}, {x:15, machine2:7},{x:12, machine2: 8}];
var groupedByX = _.groupBy(jsonData, 'x');
var result = [];
_.forEach(groupedByX, function(value, key){
var obj = {};
for(var i=0; i<value.length; i++) {
_.defaults(obj, value[i]);
}
result.push(obj);
});

I'm not sure if you're looking for pure JavaScript, but if you are, here's one solution. It's a bit heavy on nesting, but it gets the job done.
// Loop through all objects in the array
for (var i = 0; i < jsonData.length; i++) {
// Loop through all of the objects beyond i
// Don't increment automatically; we will do this later
for (var j = i+1; j < jsonData.length; ) {
// Check if our x values are a match
if (jsonData[i].x == jsonData[j].x) {
// Loop through all of the keys in our matching object
for (var key in jsonData[j]) {
// Ensure the key actually belongs to the object
// This is to avoid any prototype inheritance problems
if (jsonData[j].hasOwnProperty(key)) {
// Copy over the values to the first object
// Note this will overwrite any values if the key already exists!
jsonData[i][key] = jsonData[j][key];
}
}
// After copying the matching object, delete it from the array
// By deleting this object, the "next" object in the array moves back one
// Therefore it will be what j is prior to being incremented
// This is why we don't automatically increment
jsonData.splice(j, 1);
} else {
// If there's no match, increment to the next object to check
j++;
}
}
}
Note there is no defensive code in this sample; you probably want to add a few checks to make sure the data you have is formatted correctly before passing it along.
Also keep in mind that you might have to decide how to handle instances where two keys overlap but do not match (e.g. two objects both having machine1, but one with the value of 5 and the other with the value of 9). As is, whatever object comes later in the array will take precedence.

const mergeUnique = (list, $M = new Map(), id) => {
list.map(e => $M.has(e[id]) ? $M.set(e[id], { ...e, ...$M.get(e[id]) }) : $M.set(e[id], e));
return Array.from($M.values());
};
id would be x in your case
i created a jsperf with email as identifier: https://jsperf.com/mergeobjectswithmap/
it's a lot faster :)

How to create empty 2d array in javascript?

How do I create an empty 2D array in Javascript (without knowing how many rows or columns there will be in the new array)?
If it's a simple array var newArray = new Array(); I can assign as many elements as I want. But what about a 2D array? Can I create one without specifying the numbers of rows and columns? and how do I access the elements afterwards (myArray[0][1] or myArray[0,1])?

You can create a 6 x 6 empty array like this:
var myGrid = [...Array(6)].map(e => Array(6));
Array(6) generates an array with length = 6 and full of undefined values.
We map that array to another array full of undefined values.
In the end, we get a 6x6 grid full of undefined positions.
If you need to initialize the grid with a default value:
var value = 'foo'; // by default
var myGrid = [...Array(6)].map(e => Array(6).fill(value));
Now you have a 6 x 6 grid full of 'foo'.

Yes you can create an empty array and then push data into it. There is no need to define the length first in JavaScript. Check out jsFiddle Live Demo
Define:
const arr = [[],[]];
Push data:
arr[0][2] = 'Hi Mr.A';
arr[1][3] = 'Hi Mr.B';
Read data:
alert(arr[0][2]);
alert(arr[1][3]);
Update:
Here is also a video recommended by Brady Dowling:
Create a 2D array: ([https://www.youtube.com/watch?v=tMeDkp1J2OM][2])

There are no two dimensional arrays in Javascript.
To accomplish the effect of a two dimensional array, you use an array of arrays, also known as a jagged array (because the inner arrays can have different length).
An empty jagged array is created just like any other empty array:
var myArray = new Array();
You can also use an empty array literal:
var myArray = [];
To put any items in the jagged array, you first have to put inner arrays in it, for example like this:
myArray.push([]);
myArray[0][0] = 'hello';
You can also create an array that contains a number of empty arrays from start:
var myArray = [[],[],[]];
That gives you a jagged array without any items, but which is prepared with three inner arrays.
As it's an array of arrays, you access the items using myArray[0][1].

Say you wanted to make a 2d array (i.e. matrix) that's 100x100, you can do it in one line, like this:
var 2darray = new Array(100).fill(null).map(()=>new Array(100).fill(null));
This will create a 100x100 matrix of NULL's.
Replace the 100x100 with whatever dimensions you want, and the null's with whatever is your prefered default value, or blank for undefined.

You can use a simple for loop to create an array of the approximate size and then push more rows if need be.
const arr = [];
const n = 7;
const m = 5;
for (let i = 0; i < n; i++) {
arr.push(new Array(m).fill(0));
}
const arr = [];
const n = 7;
const m = 5;
for (let i = 0; i < n; i++) {
arr.push(new Array(m).fill(0));
}
console.log(arr);

var myArray = [
["cats","dogs","monkeys","horses"],
["apples","oranges","pears","bananas"]
];
document.write(myArray[0][2]) //returns "monkeys"

Two things:
1) The array length property improperly reports the array length if called after the var myArray = [[],[]]; statement. Technically, since the empty arrays are defined, they are getting counted by the length property, but in the spirit of the length property it really should return 0, because no non-empty elements have been added to any of the arrays.
A minimum work around is to use two nested for( in ) loops, one for the 1st array and one for the 2nd array, and to count the non-undefined elements.
2) Extending Siamak A.Motlagh example and adding a arr([2][4]) = 'Hi Mr.C'; assignment fails with an "Uncaught TypeError: Cannot set property '4' of undefined" error.
See the jsFiddle: http://jsfiddle.net/howardb1/zq8oL2ds/
Here is a copy of that code:
var arr = [[],[]];
alert( arr.length ); // wrong!
var c = 0;
for( var i in arr )
for( var j in arr[ i ] )
if( arr[ i ][ j ] != undefined )
++c;
alert( c ); // correct
arr[0][2] = 'Hi Mr.A';
alert(arr[0][2]);
arr[1][3] = 'Hi Mr.B';
alert(arr[1][3]);
arr[2][4] = 'Hi Mr.C'; // At this point I'm getting VM558:62 Uncaught TypeError: Cannot set property '4' of undefined
alert(arr[2][4]);
var c = 0;
for( var i in arr )
for( var j in arr[ i ] )
if( arr[ i ][ j ] != undefined )
++c;
alert( c );
Why does the third assignment fail? What about the [[],[]] creation statement told it that the first array was valid for 0 and 1, but not 2 or that 2 and 3 were ok for the second array, but not 4?
Most importantly, how would I define an Array in an Array that could hold date objects in the first and second arrays. I'm using the jQuery-UI DatePicker, which expects an array of dates, as in date objects, which I've extended to use a second date array to contain date objects that contain times so I can keep track of multiple dates, and multiple times per day.
Thanks.

The functions I use
function get_empty_2d_array(numRows, numColumnns) {
return [...Array(numRows)].map(e => Array(numColumnns));
}
function get_2d_array_filled(numRows, numColumnns, fillValue) {
return [...Array(numRows)].map(e => Array(numColumnns).fill(fillValue));
}

This also works as an expression:
var twoDarr= new Array(desiredLength);
for (i=0;i<twoDarr.length;i++) {twoDarr[i]=[];}
I don't know how it pars in terms of performance with the rest of the answers here, if you have a clue let me know in the comments.
If you don't know the length of the array beforehand pls have in mind that you can use either push([]), or splice() if you want to push/remove/replace a new element in place of an existing one.

const grid = new Array(n).fill(new Array(n))