Suppose in Javascript that you assign the SRC to an IMG tag. It is a large SRC and you want to cancel it before it has finished loading. Assigning the SRC to another image will not stop the data from loading.
That is, in the middle of the load you can assign the SRC to another smaller image and the smaller image will be loaded and appear in your browser. However, the original SRC still continues downloading.
Similarly, deleting the IMG node will not prevent the SRC from continuing to download. No guesses please, look at the repro steps.
REPRO
Load this URL in Chrome in Windows: http://68.178.240.17/imgLoadTest/imgLoadTest.htm
Open up the developer panel by pressing CTRL-SHIFT-J
On the top row of icons in the Chrome developer panel click the Network icon to watch network activity.
On the web page loaded in Step 1 click the Load Image button and watch the developer panel as a large (32meg) image starts loading.
On the web page click the Try To Cancel button to load a different image.
A small image loads, but watch the network in the developer panel and notice that the large image continues to download.