I haven't paid attention to the background-image attribute of the div before. I just set its URL. I encountered a problem today and I will record it here.
in js I want to get the image attribute
document.getElementById('img_2' ).style.backgroundImage;
Pay attention to the bold part, the div is background-image, and the attribute is backgroundImage. This should be done for all styles with "-". This needs to be verified.
Record this issue first to learn.