maupassant-hugo/layouts/partials/copy_button.html

{{- if (and (eq .Kind "page") (in (slice "post" "posts") .Type)) }}
<style type="text/css">
div.highlight {
    position: relative;
    margin: 1em 0px;
}

.copy-code {
    display: none;
    position: absolute;
    top: 4px;
    right: 4px;
    color: rgba(255, 255, 255, 0.8);
    background: rgba(78, 78, 78, 0.8);
    border-radius: var(--radius);
    padding: 0 5px;
    font: inherit;
    user-select: none;
    cursor: pointer;
    border: 0;
    --radius: 8px;
}

div.highlight:hover .copy-code,pre:hover .copy-code {
    display: block;
}

</style>
<script>
    document.querySelectorAll('pre > code').forEach((codeblock) => {
        const container = codeblock.parentNode.parentNode;

        const copybutton = document.createElement('button');
        copybutton.classList.add('copy-code');
        copybutton.innerHTML = 'copy';

        function copyingDone() {
            copybutton.innerHTML = 'copied!';
            setTimeout(() => {
                copybutton.innerHTML = 'copy';
            }, 2000);
        }

        copybutton.addEventListener('click', (cb) => {
            if ('clipboard' in navigator) {
                navigator.clipboard.writeText(codeblock.textContent);
                copyingDone();
                return;
            }

            const range = document.createRange();
            range.selectNodeContents(codeblock);
            const selection = window.getSelection();
            selection.removeAllRanges();
            selection.addRange(range);
            try {
                document.execCommand('copy');
                copyingDone();
            } catch (e) { };
            selection.removeRange(range);
        });

        if (container.classList.contains("highlight")) {
            container.appendChild(copybutton);
        } else if (container.parentNode.firstChild == container) {
            // td containing LineNos
        } else if (codeblock.parentNode.parentNode.parentNode.parentNode.parentNode.nodeName == "TABLE") {
            // table containing LineNos and code
            codeblock.parentNode.parentNode.parentNode.parentNode.parentNode.appendChild(copybutton);
        } else {
            // code blocks not having highlight as parent class
            codeblock.parentNode.appendChild(copybutton);
        }
    });
</script>
{{- end }}