Validating js object values, how to write better?

Question

css

Good afternoon! Please tell me how to write better.
From the code, you can understand what it should do.
You need to check the value of the objects in the array and if they match, write the value to the variable.
At the moment it works, but somehow not correctly.

list.map((item, i, arr) => {
              let park;
              if(typeof arr[i + 1] !== 'undefined') {
                if(arr[i].ln === arr[i + 1].ln) {
                  park= true;
                } else{
                  park= false;
                }
              }
})

Thank you!

Answer 1

I'm not sure that I helped you, because I didn't really understand the essence of the task, but:
https://codepen.io/anon/pen/jgMeKg

Answer 2

Either this
Either use flexbox as shown by Kirill Udaltsov
Or use css-grid

Answer 3

From the code you can understand what it should do

You can't, it doesn't work for you the way you want.
And what result do you want to get?