Search through an array, identify duplicates, and transfer them into a separate array

Question

Search through an array, identify duplicates, and transfer them into a separate array

I am working with an array of objects containing dates and I am looking to extract objects with the same date values into a new array. Below is the code snippet.

    var posts = [
  {
    "userid": 1,
    "rating": 4,
    "mood": "happy",
    "date": "2017-05-24T04:00:00.000Z"
   },
  {
    "userid": 1,
    "rating": 3,
    "mood": "happy",
     "date": "2017-05-24T04:00:00.000Z"
  },
  {
    "userid": 1,
    "rating": 3,
    "mood": "angry",
    "date": "2017-05-25T04:00:00.000Z"
  },
  {
    "userid": 1,
    "rating": 5,
    "mood": "hungry",
    "date": "2017-05-25T04:00:00.000Z"
  }]
var may25=[];

for(i=0;i < posts.length;i++){
if(posts[i].date === posts[i].date){
may25.push(posts[i].date)
}
}

javascript arrays loops

Answer 1

Answer №1

To efficiently group items by date, one approach is to extract the date from a string and use it as a key for an object. This results in an object containing all the grouped items.

var data = [{ id: 1, value: 4, status: "open", timestamp: "2019-08-15T14:30:00.000Z" }, { id: 2, value: 6, status: "closed", timestamp: "2019-08-15T16:45:00.000Z" }, { id: 3, value: 5, status: "pending", timestamp: "2019-08-16T10:20:00.000Z" }, { id: 4, value: 3, status: "resolved", timestamp: "2019-08-17T09:10:00.000Z" }],
    groups = Object.create(null);
    
data.forEach(function (item) {
    var dateKey = item.timestamp.slice(0, 10);
    groups[dateKey] = groups[dateKey] || [];
    groups[dateKey].push(item)
});

console.log(groups);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 2

To efficiently group items by date, one approach is to extract the date from a string and use it as a key for an object. This results in an object containing all the grouped items.

var data = [{ id: 1, value: 4, status: "open", timestamp: "2019-08-15T14:30:00.000Z" }, { id: 2, value: 6, status: "closed", timestamp: "2019-08-15T16:45:00.000Z" }, { id: 3, value: 5, status: "pending", timestamp: "2019-08-16T10:20:00.000Z" }, { id: 4, value: 3, status: "resolved", timestamp: "2019-08-17T09:10:00.000Z" }],
    groups = Object.create(null);
    
data.forEach(function (item) {
    var dateKey = item.timestamp.slice(0, 10);
    groups[dateKey] = groups[dateKey] || [];
    groups[dateKey].push(item)
});

console.log(groups);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 3

Answer №2

Interested in finding May 25th dates specifically? Here's a solution:

var may25Dates=[];

for (i=0;i < posts.length;i++) {
    if (posts[i].date === "2017-05-25T04:00:00.000Z") {
        may25Dates.push(posts[i].date)
    }
}

Answer 4

Interested in finding May 25th dates specifically? Here's a solution:

var may25Dates=[];

for (i=0;i < posts.length;i++) {
    if (posts[i].date === "2017-05-25T04:00:00.000Z") {
        may25Dates.push(posts[i].date)
    }
}

Answer 5

Answer №3

If you are looking to organize your data, consider creating an object that stores date => event pairs :

var collection = items.reduce((obj, event) => ((obj[event.date] = obj[event.date] || []).push(event), obj), {});

Once you have your object set up, you can easily access specific events like this:

collection["2017-05-25T04:00:00.000Z"].forEach(console.log);

Here is a breakdown of how it functions:

items.reduce((obj, event) => ...) // loops through the items and passes each one as an event to the function along with an empty object

(obj[event.date] = obj[event.date] || []) // retrieves the array for the specific date or creates a new one if none exists

.push(event) // adds our event to the array

Answer 6

If you are looking to organize your data, consider creating an object that stores date => event pairs :

var collection = items.reduce((obj, event) => ((obj[event.date] = obj[event.date] || []).push(event), obj), {});

Once you have your object set up, you can easily access specific events like this:

collection["2017-05-25T04:00:00.000Z"].forEach(console.log);

Here is a breakdown of how it functions:

items.reduce((obj, event) => ...) // loops through the items and passes each one as an event to the function along with an empty object

(obj[event.date] = obj[event.date] || []) // retrieves the array for the specific date or creates a new one if none exists

.push(event) // adds our event to the array

Search through an array, identify duplicates, and transfer them into a separate array

Answer №1

Answer №2

Answer №3

Similar questions

When you press the submit button, the screen automatically scrolls down but no action is taken

Steps for correctly displaying a success message after clicking and copying to the clipboard:

Best practice for sending a Facebook token securely between client and server

Retrieve the HTML code from a webpage on a different domain

What is the method for determining the overall page load time of a website, taking into account the total loading time instead of just the document.ready()

What is causing the click function to malfunction after selecting a second item?

Incorporate a stylish gradient background into react-chartjs-2

Which names can be used for HTML form tags in jQuery?

Looking to duplicate the elements with the click of a button?

guide on creating a simple line highchart using JSON data

input value does not change when the "keyup" event is triggered

Exploring the capabilities of the jQuery `val()` function alongside the dynamic framework

Simultaneously activate the 'onClick' and 'onClientClick' events on an ASP button using JavaScript

Sequelize JS - Opting for the On clause in join operations

Node.js is great at hosting HTML files, but struggles when it comes to loading script files within those pages

How can I achieve a similar functionality to array_unique() using jQuery?

The second instance of a React Paginate on the same page remains static and does not trigger a

Passing a return value to ajax success within an Express application

The variable "$" cannot be found within the current context - encountering TypeScript and jQuery within a module

Looking for Efficiency in Basic JavaScript Arithmetic Operations