How I can remove new lines only inside the HTML tags with preg_replace ?

Example:

<table>

<tr>

<td></td>
</tr>
</table>

Text here. Text here

Text here.

So after the functions process the above code the return should be:

<table>    <tr>    <td></td>    </tr>    </table>

Text here. Text here

Text here.

• php
• preg-replace

How I can remove new lines only inside the HTML tags with preg_replace ?

Technically yes, but actually, HTML does not care for newlines that much, every multiple whitespace characters are actually read as a single one. As your example shows, you replace \n with space or \t, so it's actually the same which brings me to the point you can just do the following:

$html = preg_replace('~(>[^>]*)(*BSR_ANYCRLF)\R([^<]*<)~', '$1 $3', $html);

See as well: php regex to match outside of html tags and How to replace different newline styles in PHP the smartest way?.

A more safe way is to use a HTML parser like DOMDocument and load your fragment as body. Then replace all newlines within textnodes that are childnodes of body childnodes.

There might be smarter ways to do this, but however, this will do your job.

$str = "test\n\n test2 <table>\n\n\n test 3</table>\n\n\n test4 test5";

while ($str2 = preg_replace('/(>[^<]*)\n([^<]*<)/', '\\1\\2', $str)) {
    if ($str2 == $str) break;
    $str = $str2;
}

echo ($str);

It looks for newlines in between the > char and the < char, and removes them.