ar.falsy.cat/assets/js/clipboard.js

const svgCopy =
    '<svg aria-hidden="true" height="16" viewBox="0 0 16 16" version="1.1" width="16" data-view-component="true"><path fill-rule="evenodd" d="M0 6.75C0 5.784.784 5 1.75 5h1.5a.75.75 0 010 1.5h-1.5a.25.25 0 00-.25.25v7.5c0 .138.112.25.25.25h7.5a.25.25 0 00.25-.25v-1.5a.75.75 0 011.5 0v1.5A1.75 1.75 0 019.25 16h-7.5A1.75 1.75 0 010 14.25v-7.5z"></path><path fill-rule="evenodd" d="M5 1.75C5 .784 5.784 0 6.75 0h7.5C15.216 0 16 .784 16 1.75v7.5A1.75 1.75 0 0114.25 11h-7.5A1.75 1.75 0 015 9.25v-7.5zm1.75-.25a.25.25 0 00-.25.25v7.5c0 .138.112.25.25.25h7.5a.25.25 0 00.25-.25v-7.5a.25.25 0 00-.25-.25h-7.5z"></path></svg>';
const svgCheck =
    '<svg aria-hidden="true" height="16" viewBox="0 0 16 16" version="1.1" width="16" data-view-component="true"><path fill-rule="evenodd" fill="rgb(63, 185, 80)" d="M13.78 4.22a.75.75 0 010 1.06l-7.25 7.25a.75.75 0 01-1.06 0L2.22 9.28a.75.75 0 011.06-1.06L6 10.94l6.72-6.72a.75.75 0 011.06 0z"></path></svg>';


const addCopyButtons = () => {
    let els = document.getElementsByClassName("highlight");
    // for each highlight
    for (let i = 0; i < els.length; i++) {
        if (els[i].getElementsByClassName("clipboard-button").length) continue;

        // find pre > code inside els[i]
        let codeBlocks = els[i].getElementsByTagName("code");

         // line numbers are inside first code block
        let lastCodeBlock = codeBlocks[codeBlocks.length - 1];
        const button = document.createElement("button");
        button.className = "clipboard-button";
        button.type = "button";
        button.innerHTML = svgCopy;
        // remove every second newline from lastCodeBlock.innerText
        button.addEventListener("click", () => {
            navigator.clipboard.writeText(lastCodeBlock.innerText.replace(/\n\n/g, "\n")).then(
                () => {
                    button.blur();
                    button.innerHTML = svgCheck;
                    setTimeout(() => (button.innerHTML = svgCopy), 2000);
                },
                (error) => (button.innerHTML = "Error")
            );
        });
        // find chroma inside els[i]
        let chroma = els[i].getElementsByClassName("chroma")[0];
        els[i].insertBefore(button, chroma);
    }
}