Get a Unique List of Objects in an Array of Object in JavaScript

To the tutorial! : yagisanatode.com/2021/07/03/g...
00:00 Intro
00:38 Build the array of objects
03:36 Write the one-liner
07:17 Alternate example
08:28 the map() method
10:52 Map object
14:17 Map object key() method
16:42 Map object values() method
17:30 spread syntax
19:08 summary
Learn a 'unique' way (pun intended) to get a distinct list of objects in an array of objects based on a shared key in JavaScript.
Bonus points if you know the name of the TH-cam series used in the example.
#JS #JavaScript #vanillaJavaScript

[@shineLouisShine]

Wow, what an tutorial, which I ran into completely by an accident.
I wasn't expected it, and it is amazingly helpful.
I'm very impressed!
Thanks a lot :))
P.S.
Just read your article after following the link at the description.
It clarify few things.
Awesome.

[@JustClickApprove92]

Instead of copying and pasting, you can highlight the code you want to copy and press alt + shift + down arrow

[@yagisanatode]

For sure. Great shortcut. Not too sure how universal the shortcut is with other editors, so stayed with copy and paste to keep it safe.

[@jeanrakotoarison1976]

great

[@AmitK]

Awesome !! now tell me , if this is possible in this example below:
[
{
userId: 1,
joinTime: 1234
},
{
userId: 2,
joinTime: 1234
},
{
userId: 1,
joinTime: 1235
},
{
userId: 2,
joinTime: 1236
},
{
userId: 1,
joinTime: 1237
}]
I need to get only unique userId's but with highest number of joinTime
e.g. [
{ userId: 1, joinTime: 1237 },
{ userId: 2, joinTime: 1236 }
}
can we somehow conditionally set new Map to select unique only where joinTime is higher, or may be , we first put all objects of the array in sorting order from lower joinTime to high joinTime and then we put it in new Map .

[@yagisanatode]

You would probably be better off using the reduce() method in your case and storing the array there. On each iteration, you could check the accumulator of your array against your item to ensure that it is the one with the highest join time.

[@swathibaby]

it really help me out thank you too much

[@yagisanatode]

Glad to hear that!

[@misterjaypeasmith]

What’s the effect of using the spread operator in the
let uniqueObjArray = [ … new Map(myObjArray -etc-]
What would happen without that?

[@yagisanatode]

Without the spread operator, you would just create a single mapped object inside an array " [map]". The spread operator iterates through the map breaking each part out to return it back to an array of objects. Hope this helps.

[@aengtech]

Thank you. I know how the new Set method work but it gives only unique value not the entire array

[@wertwertwy5]

typo on your website "spend some to"
But as many code oneliners are, they are a little tricky to understand. So I wanted to spend some to understanding how this worked and thought, you might find this a little interesting too.

[@yagisanatode]

Great find, Jesse. All updated now.

[@sindhurc7287]

How to remove duplicates objects in array

[@santhiya6615]

I need one key value from one object.how to do that .my question how to get a particular key vale from object

[@yagisanatode]

Hi Santhiya, to get an value from a key you can use myObj.keyName or myObj['keyName']. You can check if a key exists in an object with myObj.hasOwnProperty('keyName'). Apologies if this doesn't answer your question.

[@santhiya6615]

@@yagisanatode thank you

[@inainthakaikal4522]

Hi, santhiya! Do you have got an answer?
Please tell me

[@fahadhasan1436]

I think we can also use Set in place of Map to get unique objects am I correct?

[@yagisanatode]

Hi Fahad, I haven't found a good way to do this that would a) allow me to choose which property in each object that I want to check is unique across all objects. b) return the entire object for each unique item in the array. c) is a neat one-liner.
Would love to see a good Set-based solution for this 👍.

[@funnyanimalworld7579]

what is this Map with capital M?

[@yagisanatode]

Yeah. It is an unusual one. The Map constructor allows you to create map objects. At the sake of enraging the neck-beards, the simple difference is that Maps can be ordered and keys and values can be in any data type. This makes them a little more performant when you need an object that you will add and remove to frequently. developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/Map medium.com/front-end-weekly/es6-map-vs-object-what-and-when-b80621932373

[@devika3242]

I want number of people.. how to get?

[@yagisanatode]

In the example we are using an object array of people so all you need to do is use the 'length' method >> myObjArray.length

[@devika3242]

How to store a file content in to a object

[@yagisanatode]

That's a tricky one and depends on a lot of factors. For example, what platform are you reading the file from, browser, Node.js, Apps Script? What is the file type? What type of data are you trying to extract and insert?
Add you iterate over your data you can add it to your Object in a number of ways: developer.mozilla.org/en-US/docs/Learn/JavaScript/Objects/Basics

[@devika3242]

@@yagisanatode i want to covert the file content to store or add object and extract the number of content in file and another summary.. like student details in file content that read and store it to object.. how that possible?? I used in nodejs. File is text file..

[@yagisanatode]

A common approach in Node.js would be to use the fs module with the readFile() method. nodejs.org/en/knowledge/file-system/how-to-read-files-in-nodejs/
You would need to use regular expressions to match the areas that you want to extract from the files. javascript.plainenglish.io/learn-to-use-regular-expressions-like-a-ninja-in-node-js-20cfb6806f26