js获取浏览器私有css样式前缀

export const vendorPrefix = (function() {
  if (typeof window === 'undefined' || typeof document === 'undefined') return ''; // server environment
  // fix for:
  //    https://bugzilla.mozilla.org/show_bug.cgi?id=548397
  //    window.getComputedStyle() returns null inside an iframe with display: none
  // in this case return an array with a fake mozilla style in it.
  const styles = window.getComputedStyle(document.documentElement, '') || ['-moz-hidden-iframe'];
  const pre = (Array.prototype.slice.call(styles).join('').match(/-(moz|webkit|ms)-/) || (styles.OLink === '' && ['', 'o']))[1];

  switch (pre) {
    case 'ms':
      return 'ms';
    default:
      return pre && pre.length ? pre[0].toUpperCase() + pre.substr(1) : '';
  }
})();