Javascript两个感叹号的用法（!!）

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var foo;  
alert(!foo);//undefind情况下或者null，一个感叹号返回的是true;  
alert(!goo);//undefind情况下，一个感叹号返回的也是true;  但是这里会报undefind的错误
var o={flag:true};  
var test=!!o.flag;//等效于var test=o.flag||false;  
alert(test);  //返回true
var test2=!!o.flag1;//当里面没有对象时
alert(test2);//返回false
var test3=!!b.flag;//当连b这个对象都没有时
alert(test3);//返回false

from:https://www.cnblo […]

基于dynamic，动态给强类型Model扩展属性

直接上代码

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            List<TestModel> testList = new List<TestModel>();
            testList.Add(new TestModel { Id = 1, Name = "A" });
            testList.Add(new TestModel { Id = 2, Name = "B" });
            testList.Add(new TestModel { Id = 3, Name = "C" });
 
            List<dynamic> test = new List<dynamic>();
            foreach (var item in testList)
            {
                dynamic dobj = new System.Dynamic.ExpandoObject();
                var dic = (IDictionary<string, object>)dobj;
 
                var t = item.GetType();
                var properties = t.GetProperties();
                // 循环赋值原Model中的值
                foreach (var propertyInfo in properties)
                {
                    var propertyName = propertyInfo.Name;
                    dic[propertyName] = propertyInfo.GetValue(item);
                }
 
                // 动态扩展属性
                dic["Age"] = 3;
 
                test.Add(dic);
            }

  示例Model [ […]