DEMOs

.copy-to-clipboard {
  margin-bottom: torem(20px);

  .input {
    width: torem(260px);
    font-size: torem(12px);
    line-height: 1.5;
    border: 1px solid var(--grey);
    padding: torem(5px) torem(2px);
  }

  .btn {
    height: torem(30px);
    border: 1px solid var(--grey);
    padding: 0 torem(3px);
    margin-left: torem(10px);
    cursor: pointer;
  }
}

/**
 * 点击事件处理函数
 */
function handler(e) {
  const { copytarget } = e.target.dataset;
  const inp = copytarget ? document.querySelector(`#${copytarget}`) : null;

  if (inp && inp.select) {
    inp.select();

    try {
      document.execCommand('copy');
      inp.blur();
    } catch (err) {
      console.log('please press Ctrl/Cmd+C to copy'); // eslint-disable-line no-console
    }
  }
}

document.addEventListener('DOMContentLoaded', () => {
  document.body.addEventListener('click', handler, false);
});