WordPress minify html only in the main page

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I was using this code to minify HTML output in wordpress.
It works perfect on the main page and on the post page, but in the admin section it causes a lot of problems. 

function minify_html(){
    ob_start('html_compress');
}

function html_compress($buffer){

    $search = array(
        '/n/',         // replace end of line by a space
        '/>[^S ]+/s',     // strip whitespaces after tags, except space
        '/[^S ]+</s',     // strip whitespaces before tags, except space
        '/(s)+/s',     // shorten multiple whitespace sequences,
        '~<!--//(.*?)-->~s' //html comments
    );

    $replace = array(
        ' ',
        '>',
        '<',
        '\1',
        ''
    );

    $buffer = preg_replace($search, $replace, $buffer);

    return $buffer;
}

add_action('wp_loaded','minify_html');

Using ‘the_post’ instead of ‘wp_loaded’ minifies only the posts, but I’d like to be able to minify at 100% the main page, and the post page, but nothing in the admin section.
How can I combine the actions in order to manage it?

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Thank you!

Post Views: 1

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2 comments

  1. Nice Code, exclude admin :

    if (!(is_admin() )) {
function minify_html(){
    ob_start('html_compress');
}

function html_compress($buffer){

    $search = array(
        '/n/',         // replace end of line by a space
        '/>[^S ]+/s',     // strip whitespaces after tags, except space
        '/[^S ]+</s',     // strip whitespaces before tags, except space
        '/(s)+/s',     // shorten multiple whitespace sequences,
        '~<!--//(.*?)-->~s' //html comments
    );

    $replace = array(
        ' ',
        '>',
        '<',
        '\1',
        ''
    );

    $buffer = preg_replace($search, $replace, $buffer);

    return $buffer;
}

add_action('wp_loaded','minify_html'); }

    It works well WP admin !

  2. There is a troubleshoot case where replacing empty space with preg_replace causes invalid characters with UTF-8. (eg: à encoding would fail and result in �). This is due to a mismatch between the current locale and the defined locale. We can use the /u flag as a way to properly filter UTF-8 characters.

    In some instances, removing new lines and multiple spaces from inline <script> tags will cause the script to break. Isolating the <script> tag’s content will prevent this from happening which is done by splitting the buffer into an array delimited by opening and closing script tags through preg_split().

    <?php

/**
 * Turn on output buffering, prettify and minimy the HTML output.
 * 
 * @see https://www.php.net/manual/en/function.ob-start.php
 * 
 * @since 1.0.0
 */
add_action( 'wp_loaded', function () {

    ob_start( function ( $buffer ) {

        /**
         * preg_replace() UTF-8 troubleshooting.
         * 
         * Replacing empty space with preg_replace causes invalid characters with UTF-8.
         * As preg_replace() depends on the current defined locale, characters not supported will be returned as � invalid.
         * The /u flag is used to make regex unicode aware.
         * 
         * @see https://stackoverflow.com/a/74101068/3645650
         */
        $replace = array(
            '/n/smu'                   => '',      //Remove new lines.
            '/(s)+/smu'                => '\1',   //Replace multiple spaces with a single one.
            '/s*<s*/smu'              => '<',     //Remove spaces before and after opening tags.
            '/s*>s*/smu'              => '>',     //Remove spaces before and after closing tags.
            '/s*/>s*/smu'            => '>',     //Remove spaces before and after closing tags for self closing tags.
            '/<!--(.|s)*?-->/'         => '',      //Remove HTML comments.
            '/s*=s*'([^']*)'/smu'  => '="$1"', //Replace single quotes with double quotes within attributes.
        );
        
        /**
         * preg_replace() inline <script> troubleshooting.
         * 
         * In some instances, removing new lines and multiple spaces from inline <script> tags will cause the script to break.
         * Isolating the <script> tag's content will prevent this from happening which is done by splitting the buffer into an array delimited by opening and closing script tags through preg_split().
         * 
         * @see https://stackoverflow.com/a/10423788/3645650
         */
        $buffer = preg_split( '/(</?script[^>]*>)/', $buffer, null, PREG_SPLIT_DELIM_CAPTURE );

        foreach ( $buffer as $key => $value ) {

            //If the $key is a <script> opening tag, $key + 1 is the script tag's content, $key + 2 is the script closing tag.
            if ( false !== stripos( $value, '<script' ) ) {

                $k = $key;

            };

            //$key + 1 is the script tag's content, which we want to ignore.
            if ( $k + 1 === $key ) {

                unset( $k );

                continue;

            };

            $buffer[ $key ] = preg_replace( array_keys( $replace ), array_values( $replace ), $value );

        };

        return implode( '', $buffer );

    } );

} );

/**
 * Get current buffer contents and delete current output buffer.
 * 
 * @see https://www.php.net/manual/en/function.ob-get-clean.php
 * 
 * @since 1.0.0
 */
add_action( 'shutdown', function () {

    ob_get_clean();

} );

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