As others already explained you showed the equivalent of a foreach in JS but asked for a grep, where at best a map would make sense.

And you already got excellent replies!

But for completeness Perl is flexible enough to create your own syntactic sugar for this task

use v5.12;
use warnings;
use Data::Dump qw/pp dd/;

our $c;  # count

sub cmap(&@) {
    my $block = shift @_ ;

    local $c=-1;
    map { $c++; &$block } @_;
}

# -------- DEMO

my @myArray = qw(alfa beta gamma);

say "--- used as loop";
cmap { say "at position $c there is $_" } @myArray;

say "--- used as map";
dd cmap { [ $c => $_] } @myArray;

[download]

--->

    
--- used as loop
at position 0 there is alfa
at position 1 there is beta
at position 2 there is gamma
--- used as map
([0, "alfa"], [1, "beta"], [2, "gamma"])

[download]

Cheers Rolf
(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :)
Wikisyntax for the Monastery

In reply to Re: grep { } positional number of element by LanX
in thread grep { } positional number of element by leszekdubiel

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