Reputation: 6164
I'm scratching my head on this one. I'm trying to write a function that takes an array arr
and an integer n
and outputs a new array made up of each n-th element (starting at index 0) of the original array, returning to the beginning if necessary when the end is reached.
For instance:
arr = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
n = 3
output = [0, 3, 6, 9, 1, 4, 7, 2, 5, 8]
Or :
arr = [0, 1, 2, 3, 4, 5, 6]
n = 2
output = [0, 2, 4, 6, 1, 3, 5]
Upvotes: 1
Views: 439
Reputation: 3032
This should work:
function get_n_elements(arr, n) {
if ( n === 1 ) return arr.slice();
var i, j,
len = arr.length,
ret = [];
for ( i = 0; i < n; i++ ) {
for ( j = i; j < len; j += n ) {
ret.push( arr[ j ] );
}
}
return ret;
}
Upvotes: 4