code: function classToPlantObject(str){
  	if ( str == null ) {
  		return {};
  	}
  	if ( isPlainObject(str) ) {
  		return str;
  	}
  
  	let ary = str.split(/\s/);
  	let objCls = {};
  	ary.forEach(v => v.trim() && (objCls[v]=1));
  	return objCls;
  }
docs: "abc def" => {abc:1, def:1}