Using new Image () can only request for the case not to return data, for example, I wrote here a Demo, Logo An example of Baidu's request:
<html> <head> </head> <body> hello </body> </html> <script> var img=new Image(); img.src="https://www.baidu.com/img/superlogo_c4d7df0a003d3db9b65e9ef0fe6da1ec.png?where=super"; </script>
This page will show up inside a hello, mainly to see the following js request, I use to fill in the new Image page address directly, and then the browser F12 view, you can see there is no data returned:
This general scheme for Buried program, such as CNZZ, we only need to transmit data sent to it, and without any feedback, thus reducing the bandwidth.