journal/templates/js/code_copy.js

const copyButtonLabel = "Copy Code";

// use a class selector if available
if (navigator.clipboard) {
  let blocks = document.querySelectorAll("pre");

  blocks.forEach((block) => {
    // only add button if browser supports Clipboard API
      let button = document.createElement("button");

      button.innerText = copyButtonLabel;
      block.parentNode.insertBefore(button, block);

      button.addEventListener("click", async (event) => {
        await copyCode(block, event.target);
      });
  });
}

async function copyCode(block, button) {
  let code = block.querySelector("code");
  let text = code.innerText;

  await navigator.clipboard.writeText(text);

  // visual feedback that task is completed
  button.innerText = "Code Copied";

  setTimeout(() => {
    button.innerText = copyButtonLabel;
  }, 700);
}