效果图

实现代码

CSS部分：

将本CSS代码放置子比主题设置->全局&功能->自定义CSS样式中

JS部分：主题设置->全局&功能->自定义javascript代码

/* 
 *作者：天亦网
 *天亦网 www.catxe.com
 */
if(document.querySelectorAll(".but-download .badg")!=undefined){
     const reg = /[a-zA-z0-9]/ig;
    const copy1 = document.querySelectorAll(".but-download .badg");
    for (let i = 0; i < copy1.length; i++) {
      copy1[i].index = i;
      copy1[i].setAttribute("data-before", "点击复制");
      copy1[i].addEventListener("click", copyOperation);
      copy1[i].addEventListener("mouseout", copyOk);
    }
    function copyOperation() {
      var oInput = document.createElement("input");
      let text = this.innerText;
      text = text.match(reg).join("");
      oInput.value = text;
      document.body.appendChild(oInput);
      oInput.select();
      document.execCommand("Copy");
      oInput.className = "oInput";
      oInput.style.display = "none";
      this.setAttribute("data-before", "已复制");
    }
    function copyOk() {
      setTimeout(() => {
        this.setAttribute("data-before", "点击复制");
      }, 300)
    }
}