docs/daprdocs/static/js/copy-code-button.js

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

        button.addEventListener('click', function() {
            clipboard.writeText(codeBlock.textContent).then(
                function() {
                    button.blur();

                    button.innerText = 'Copied!';
                    setTimeout(function() {
                        button.innerText = 'Copy';
                    }, 2000);
                },
                function(error) {
                    button.innerText = 'Error';
                    console.error(error);
                }
            );
        });

        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);
        }
    });
}

if (navigator && navigator.clipboard) {
    addCopyButtons(navigator.clipboard);
} else {
    var script = document.createElement('script');
    script.src =
        'https://cdnjs.cloudflare.com/ajax/libs/clipboard-polyfill/2.7.0/clipboard-polyfill.promise.js';
    script.integrity = 'sha256-waClS2re9NUbXRsryKoof+F9qc1gjjIhc2eT7ZbIv94=';
    script.crossOrigin = 'anonymous';

    script.onload = function() {
        addCopyButtons(clipboard);
    };

    document.body.appendChild(script);
}