Is this what you need? Is the content of the two source files something akin to what you're working with?

#!/usr/bin/perl
use strict;
use warnings;

# 777297

my $data_file = "test1.txt";
open(DATA, $data_file) || die("Could not open file!");
my @data_file = <DATA>;

my $names_file = "code.txt";

open(NAMES, $names_file || die "Could not open file!");
my @names_data = <NAMES>;

# create loop that reads each ID in code.txt (NAMES array), searches f
+or each in array elements for #test1.txt 
# (DATA array), redirects a new (NAMES).html for each element

my ($names, $data);
for $names(@names_data) {
    chomp($names);
    for $data(@data_file) {
        chomp ($data);
        if ($data =~ /$names/) {
            print "found \$data ( $data )  in \$names \n";
        }
    }
}

close NAMES;
close DATA;

[download]

test1.txt:

12345
34567
89246
54321
98765

[download]

code.txt:

<html>
<head>
<title "777297 code"</title>
</head>
<body>

<p><span class="b">12345 </span> foobar</p>
<p><span class="b">54321 </span></p>
<ul><li>89246</li></ul>
<div id="second">34567
<br>78912 but this one ain't there</div>
</body>
</html>

[download]
If so, you weren't too far off.

But please, when you post code, use <code>...</code> (or <c>...</c> tags) around code and data.

Update, in light of OP's update:
The above produces this output:

found $data ( 12345 )  in $names
found $data ( 34567 )  in $names
found $data ( 89246 )  in $names
found $data ( 54321 )  in $names
found $data ( 98765 )  in $names

[download]

So now you need to add the appropriate code to create a new file for each printed line of output and print the content of names therein.

And two BTW's:

In reply to Re: Line by line parsing from one file, comparing line by line to another file by ww
in thread Line by line parsing from one file, comparing line by line to another file by web_developer

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
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