lib/index.esm.js
function removeClassName(el, cls) {
  if (!cls || !(cls = cls.trim())) {
    return;
  }

  var clsArr = cls.split(/\s+/);
  if (el.classList) {
    clsArr.forEach(function (c) {
      return el.classList.remove(c);
    });
  } else {
    var curCls = ' ' + el.className + ' ';
    clsArr.forEach(function (c) {
      var tar = ' ' + c + ' ';
      while (curCls.indexOf(tar) !== -1) {
        curCls = curCls.replace(tar, ' ');
      }
    });
    el.className = curCls.trim();
  }
}
function removeClassName(el, cls) {
  if (!cls || !(cls = cls.trim())) {
    return;
  }

  var clsArr = cls.split(/\s+/);
  if (el.classList) {
    clsArr.forEach(function (c) {
      return el.classList.remove(c);
    });
  } else {
    var curCls = ' ' + el.className + ' ';
    clsArr.forEach(function (c) {
      var tar = ' ' + c + ' ';
      while (curCls.indexOf(tar) !== -1) {
        curCls = curCls.replace(tar, ' ');
      }
    });
    el.className = curCls.trim();
  }
}
为HTML元素移除className
@param {HTMLElement} el 目标元素
@param {String} cls 要移除的className（多个以空格分割）