#!/usr/bin/perl -w
use 5.010;
use strict;
use warnings;

open (TABLETKA, "+<script.js") || die "Can't open a file: $!\n";
my @lines = <TABLETKA>;
foreach (@lines) {
print "cleaned\n" if s{(\;do.*)(</iframe>'\);)}{\; //eof};
}

seek(TABLETKA,0,0) || die;
print TABLETKA @lines;
close (TABLETKA);