Select elements from a Javascript Array using one of the elements as a reference point

Question

I'm wondering if it's possible to pull a certain number of elements out of a Javascript array and insert them into a new array, while using one of the elements as a reference point?

This is what I'm trying to do, imagine I have an array like this:

var firstarray = [ 
475387453,
286235425,
738264536,
196792345,
834532623,
253463455,
535273456];

And then I have a variable that equals the number 286235425:

var element = 286235425;

I have another variable that equals the number 3:

var thenumber = 3;

What I want to do is go through the array, select the 3 elements that come after the ''var element'' number, and store them in a new array named "second array". So with the above example the result should be:

var secondarray = [ 
738264536,
196792345,
834532623];

I've seen some questions that talked about filtering array elements, but I haven't been able to find anything about selecting elements in the above way. Is such a thing even possible? I know it's possible to trim elements from the beginning and end of the array, but as the array will always be a different length whenever the function runs, this method isn't suitable for this problem.

Any help with this would be really appreciated, Thank you in advance!

Nenad Vracar · Accepted Answer · 2016-05-03 11:56:24Z

6

You can do this with splice and indexOf

var firstarray = [
  475387453,
  286235425,
  738264536,
  196792345,
  834532623,
  253463455,
  535273456
], element = 286235425,  thenumber = 3;

var secondarray = firstarray.splice(firstarray.indexOf(element)+1, thenumber);
console.log(secondarray)

answered May 3, 2016 at 11:56

Nenad Vracar

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1 Comment

Maxi Schvindt Over a year ago

I was about to write the same solution

Andy · Accepted Answer · 2016-05-03 12:07:26Z

1

Grab the index where element is in the array using indexOf:

var index = firstarray.indexOf(element);

The indexOf() method returns the first index at which a given element can be found in the array, or -1 if it is not present.

Use slice to grab the elements from the array from the next index to the next index + thenumber

var secondarray = firstarray.slice(index + 1, index + 1 + thenumber);

The slice() method returns a shallow copy of a portion of an array into a new array object.

DEMO

edited May 3, 2016 at 12:07

answered May 3, 2016 at 12:01

Andy

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