Increases the weight for headings

functions.php

<?php

add_filter( 'relevanssi_post_content', 'rlv_heading_boost' );
function rlv_heading_boost( $content ) {
    if ( preg_match_all( '/<h1.*?>(.*?)<\/h1>/', $content, $h1_headings ) ) {
        foreach ( $h1_headings[1] as $heading ) {
            $content .= " $heading $heading $heading $heading $heading $heading $heading $heading";
        }
    }
    if ( preg_match_all( '/<h2.*?>(.*?)<\/h2>/', $content, $h2_headings ) ) {
        foreach ( $h2_headings[1] as $heading ) {
            $content .= " $heading $heading $heading $heading";
        }
    }
    if ( preg_match_all( '/<h3.*?>(.*?)<\/h3>/', $content, $h3_headings ) ) {
        foreach ( $h3_headings[1] as $heading ) {
            $content .= " $heading $heading";
        }
    }
    return $content;
}