Js pay attention to img image onerror event analysis _ javascript skills

When the webpage is opened, Stackoverflowatline: 0 is displayed. Details of the onerror event of the img image. After analysis, we found that the webpage contains code similar to the following:


Analysis: pay special attention to onerror. When the image does not exist, onerror is triggered, while onerror specifies a NoPic.gif image for img. That is to say, if an image exists, pic.gif is displayed. If the image does not exist, noPic.gif is displayed. However, the problem arises. If noPic.gif does not exist, the onerror will be triggered again, resulting in a loop.

NOTE: If an image exists but the network is not smooth, an onerror may also be triggered.

Solution:

First, remove the onerror code, change the onerror code to another, or make sure that the image in the onerror is small enough and exists.

Second:

The Code is as follows: