CSS: #id .class VS .class performance. Which is better?
I'd assume that this would be faster:
#dialog .videoContainer { width:100px; }
than:
.videoContainer { width:100px; }
Of course disregarding that .videoContainer
in the first example would only be sty开发者_如何学Pythonled under the #dialog
tag.
CSS selectors are matched from right to left.
Therefore, .videoContainer
should be "faster" than #dialog .videoContainer
because it misses out testing for #dialog
.
However, this is all irrelevant at best - you'll never notice the difference. For normally sized pages, the amount of time we're talking about is so insignificant as to be nonexistent.
Here's a relevant answer by an expert that you should read: Why do browsers match CSS selectors from right to left?
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