replace in all text nodes (html dom javascript)

helper.js

function replace_in_textnodes(search_string, replace_string) {
    console.group('replace_in_pre');
    // based on: https://stackoverflow.com/a/10730777/574981
    const walk = document.createTreeWalker(
      document,
      NodeFilter.SHOW_TEXT,
      null,
      false
    );
    let replace_counter = 0;
    const search_regex = new RegExp(search_string, 'gim');
    var text_node;
    while (text_node = walk.nextNode()) {
        let original_content = text_node.nodeValue;
        let new_content = original_content.replace(
            search_regex,
            replace_string
        );
        if (new_content != original_content) {
            replace_counter += 1;
            text_node.nodeValue = new_content;
        }
    }
    console.log('found ' + replace_counter + ' occurrences.');
    console.groupEnd();
}