TCP works in the Transport layer, IP in the Network layer, and ARP in the DataLink layer; The data on the second layer is called Frame, the data on the third layer is called Packet, and the data on the fourth layer is called Segment. At the same time, we need to simply know that when data is sent from the application layer, header information will be added to each layer, encapsulated, and then sent to the data receiving end. This basic process you need to know, that is, every data will go through the process of data encapsulation and unencapsulation.老鳖等人齐声大喊：恭请将军出阁。自己做过的事，还不能让人说？赵坤嗤笑一声。The first scheme is to use the general coding method to realize the preloading technology of the picture. First, create the imgNode element, Then when the method myImage.setSrc is called, a preloaded picture is given to the picture first, and when the picture is loaded, the img element is assigned a value. The second scheme is implemented by using proxy mode. MyImage function is only responsible for creating img elements, proxy function ProxyImage is responsible for setting loading pictures for the picture, and when the picture is really loaded, myImage.setSrc method in myImage is called to set the path of the picture. The advantages and disadvantages between them are as follows:赵军知道我们在井陉之内，摆开阵势在井陉口外等我们，是做梦想要一战就打败我们。　　还是在这一年，整个中原武林进入了最动荡的时节。大任