blog - How to Add Copy to Clipboard Buttons to Code Blocks in Hugo - add-buttons

add-buttons.js

document.querySelectorAll('pre > code').forEach(function (codeBlock) {
    var button = document.createElement('button');
    button.className = 'copy-code-button';
    button.type = 'button';
    button.innerText = 'Copy';

    var pre = codeBlock.parentNode;
    if (pre.parentNode.classList.contains('highlight')) {
        var highlight = pre.parentNode;
        highlight.parentNode.insertBefore(button, highlight);
    } else {
        pre.parentNode.insertBefore(button, pre);
    }
});