Compressing HTML in PHP (no comments or whitespace)

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In addition to compressing CSS in PHP I’ve been compressing HTML. My HTML compressor is a bit of a hack. It doesn’t handle CDATA sections for instance. But it should generally work OK. Here it is:

function slib_compress_html( $buffer ) {
  $replace = array(
    "#<!--.*?-->#s" => "",      // strip comments
    "#>\s+<#"       => ">\n<",  // strip excess whitespace
    "#\n\s+<#"      => "\n<"    // strip excess whitespace
  );
  $search = array_keys( $replace );
  $html = preg_replace( $search, $replace, $buffer );
  return trim( $html );
}

I use this function to compress HTML generated by my PHP scripts by putting ob_start( ‘slib_compress_html’ ) at the beginning of my script (after the ob_gzhandler) and ob_end_flush() at the end. My HTML compression code looks like this:

    if ( extension_loaded( 'zlib' ) ) { ob_start( 'ob_gzhandler' ); }
    ob_start( 'slib_compress_html' );

    run_app( $app_factory );

    ob_end_flush();
    if ( extension_loaded( 'zlib' ) ) { ob_end_flush(); }

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