YSlow: Avoid empty src or href
Overview
Empty src or href attributes can cause multiple problems.
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Details
You might expect a browser to do nothing when it encounters an element with an empty src or href attribute, however this is not the case in a considerable number of browsers. As of 2016, IE and Edge will both make a request to the page’s parent directory, while Firefox and older Webkit browsers (like Safari) will re-request the page itself! This behavior could potentially corrupt user data, waste server computing cycles generating a page that is never viewed, or in the worst case, cripple your servers by sending them a large amount of unexpected traffic.
Problem Element–Attribute Pairs in Modern Browsers
According to our research, these three pairs will cause needless requests in IE 10+ & all versions of Edge:
Likewise, these two appear to affect all versions of Firefox:
