Transform object properties using a comparator function in Lodash's uniqWith method

I am considering using lodash's uniqWith to remove duplicates from an array of objects. However, I also want to modify each object in the array while comparing them. My idea is to add some additional logic within the comparator function to handle both tasks without setting up another loop. Is it acceptable to include extra logic like this in the comparator function?

import uniqWith from 'lodash/uniqWith';

const transformedArray = uniqWith(
    arrayOfObjects,
    (currObject, otherObject): boolean => {

        // Implementing changes to current object properties here, is this a good approach?

        if (<someCondition>) {
            currObject.someProperty = true;
        }

        // Comparison logic between objects

        if (currObject.uuid === otherObject.uuid) {
            return true;
        }
        return false;
    },
);

Answer №1

When looking at the uniqWith documentation, it only provides limited information about how the callback function is invoked:

The comparator receives two arguments: (arrVal, othVal).

In my opinion, using the uniqWith compare function for iteration work may not be ideal. The documentation does not specify the frequency or order of calls to the compare function. Consider having an array like [1,2,3]. It could be assumed that each element is compared against all elements in the output to ensure uniqueness. A potential implementation might resemble the following:

function uniqWith(array, compareFn) {
  const unique = [];
  for (const current of array) {
    const isDuplicate = unique.some(other => compareFn(current, other));
    if (!isDuplicate) unique.push(current);
  }
  return unique;
}

If this assumption holds true, then the callback would never be called for 1, once for 2, and twice for 3.

Generally speaking, it is advised not to use callback functions for iteration tasks unless the function explicitly outlines when, how often, and in what order the callback will be executed.

For example, consider the Array forEach method. Its documentation provides detailed information on these aspects.

forEach() triggers a provided callback function once for every element in an array, in ascending order. It does not run for index properties that have been deleted or are uninitialized. (For sparse arrays, refer to the example below.)

Answer №2

Simply put: no, unless you consider it a critical problem.

More detailed response: Making changes in unconventional areas shouldn't disrupt the process. However, it's important to remember that altering code in unexpected places sacrifices clarity for conciseness – this could result in confusion and difficulties with debugging in the future if those changes are overlooked.

Answer №3

Upon conducting a more rigorous examination, it has come to my attention that there are certain optimizations implemented in the lodash/uniqWith function where not every item is passed to the comparator function as the currObject. Therefore, in relation to the code provided in the initial inquiry, it cannot be assumed that each item in the array will have its .someProperty = true. I acknowledge that I should have conducted further testing before posting, but I am grateful for the valuable feedback.

Similar questions

If you have not found the answer to your question or you are interested in this topic, then look at other similar questions below or use the search

Steps for setting a JavaScript variable to contain an NDJSON value

I am attempting to store the information from an ndjson file into a JavaScript variable. I have experimented with using both arrays and objects, but encountered errors in the process. This is what I tried: var data = [{"attributes":{}} {"attributes":{}} ...

How can I complete this .js file and .ejs file in NodeJS (Express) to query the object ID in my browser?

My goal is to query an objectID from MongoDB using NodeJS and then retrieve it on my local host through http://localhost:3000/objectSearch?objectid= I've searched everywhere, but I can't seem to figure it out. If someone could provide me wi ...

Problem arising from the transition between Q library versions 0.9.6 and 0.9.7

My experience with the q library was successful in processing ajax data sequentially. Each ajax call is followed by a.then( function(){} ) to ensure proper sequencing. During the processing of individual data entries, I display the ajax result on screen u ...

Error: Unable to access the 'rotation' property of an undefined object in the animate function on line 266 of index.html, at line 287 of index.html

I am facing an error when trying to animate a model with rotation or position in my code. I attempted to create an init function to run everything, but it did not resolve the issue. The error only appears during animation; once the animation stops, the e ...

Retrieve data from a JavaScript generator-stream by applying a filter to the values

After watching a thought-provoking video on computerphile, I was inspired to try my hand at implementing the sieve algorithm using JavaScript generators. While I have experience with JavaScript, working directly with generators is a new challenge for me. ...

JavaScript loop to process form submissions

Running a for loop through data retrieved from the Facebook API, my goal is to store this data in my own database for use on other websites. The issue arises during the submission process, as it seems I can only submit once. The culprit appears to be the ...

Configuring Socket.io for handling 404 errors

On my LAMP server, I have both apache and server.js running along with an index.html file: <html> <head> <script src="/socket.io/socket.io.js"></script> </head> <body> <script> ...

From JavaScript to a jQuery AJAX call

My Javascript code utilizes Ajax to send a request to my Tomcat server. I have configured a filter on the server to allow cross domain requests by setting up the following: <filter> <filter-name>CorsFilter</filter-name> <filte ...

Send the user to the chosen option in the dropdown menu

My goal is to redirect the user based on the option they select. I am having an issue with my HTML code as it currently redirects to "example.com/page" instead of "example.com/page/1". Can someone please assist me in resolving this problem? <select clas ...

Focus on a particular div in order to enable scrolling beyond its boundaries

Whenever I move my mouse over the div tag, I am able to scroll the content. However, if I move the mouse outside of the div box, scrolling stops. Is there a way to make the specific div element track the mouse pointer no matter where it goes? <div st ...

Labels can sometimes cause text input fields to become unresponsive

I've encountered a bug while working on my website with the materializecss framework. Sometimes, inputs are not responding correctly. This issue seems to occur when clicking on the first input and accidentally targeting the higher part of the second ...

The website that had been functioning suddenly ceased operations without any modifications

It seems like this might be related to a JavaScript issue, although I'm not completely certain. The website was working fine and then suddenly stopped. You can find the URL here - Below is the HTML code snippet: <!DOCTYPE html> <html> ...

HTML5: Enhancing Video Playback on the iPad with Custom Zoom Controls

I've customized a smaller UIWebView specifically for the iPad, and I've created my own HTML5 controls for the video playback. However, when I try to maximize the video, all I see is a black screen instead of the actual content. The audio still pl ...

checking if the height of the body is less than 100% using javascript or jquery

On my website, I didn't set a height for the html or body tags. This setup works well on pages with ample content, but when a page has insufficient content, I want the body height to be 100%. I decided to try using jQuery to solve this issue. I came ...

Retrieve data from a list using an API

I am currently working on creating a dynamic list by fetching data from an API. The goal is to display detailed information in a modal when a user clicks on a specific item in the list. While the list itself is functioning properly, I am encountering an i ...

How can we incorporate an algorithmic solution into an Angular brand carousel?

I am seeking to create a brand slider in Angular without relying on any external libraries or packages. The functionality I desire is as follows: 1 2 3(active) 4 5 2 3 4(active) 5 6 3 4 5(active) 6 7 4 5 6(active) 7 (empty) 5 6 7(active) (empty) (empt ...

Error message in Mysql connector for NodeJS: Pool has been closed

We have developed a NodeJS application that functions as an API for a frontend Angular project we are currently working on. So far, both components have been operating smoothly. However, occasionally we encounter a strange error with the API stating "Pool ...

Generate different choices in a DropDownList depending on the selection made in another DropDownList using JavaScript

I am currently working on implementing a search panel that will populate items based on the minimum and maximum price criteria. When looking at the front view of my page, it appears as follows: For instance, if I select a minimum price value of 100,000, t ...

Discovering the necessary WebGL browser Add-ons

I have been developing a WebGL application using ThreeJs to showcase 3D models with various effects (shaders). In order to test if the user's browser can run the app, I need to retrieve a list of supported plugins. The Query: My main dilemma is deter ...

Tips for executing a jQuery nested template in a recursive manner

Imagine a world where JSON objects and jQuery templating collide in a thought-provoking inception-like scenario. How can we dive deeper into this rabbit hole? The catch is, I'm a bit lazy and hoping the code will do most of the heavy lifting... Q:& ...