sizzle

I have been reading more lately about the efficiency of the different selector engines. I know that jQuery uses the Sizzle engine and this blog post about some jQuery stuff mentioned that the Sizzle engine will break apart your selector into an array then parse left to right. It then, from right to left, begins deciphering each item with regular expressions. What this also means is that the right-most part of your selector should be as specific as possible — for instance, an id or tag name. My question is whether it is more efficient to run a selector with just the ID specified or the tag name

Ok saddle up cowboys, because this is going to be a long one. I have been spending the morning going through some of my old code and I'm left wondering about best practices and optimzation. In order to avoid a ride down subjective lane I'll just post some examples with some hopefully easy to answer questions. I will try to keep the examples very simple for ease of an answer and to decrease the likelihood of mistakes. Here we go: 1) Assignment vs jQuery Calls I understand that when accessing selectors it's generally considered better to assign a selector to a variable rather than make the same

I was just browsing Sizzle's source code and I came across this line of code: array = Array.prototype.slice.call( array, 0 ); I looked up what the function is, but I came to the conclusion that it just returns all elements of the array starting from index 0, and puts the whole into the array, i.e. it doesn't really do anything at all. What is therefore the use of this line of code? What am I missing? Edit: It's line 863 from https://github.com/jquery/sizzle/blob/master/sizzle.js#L863 . The DOM usually returns a NodeList for most operations like getElementsByTagName . Although a NodeList almost

Is there a standard or reliable method already out there for a javascript framework such as jquery to parse a stylesheet into an object? Two reasons for why I'm wondering: I have seen a couple of questions where someone wanted to know how to get the style attribute that was set by the stylesheet for a selector, not what the selector eventually inherited. If Sizzle does what it is supposed to, this could be a solution for making sure a stylesheet got rendered correctly cross-browser. Basically have jquery parse the stylesheet and set all of the attributes manually (maybe based on browser or

Apparently, as I've discovered while commenting on another answer , jQuery (rather its underlying selector engine Sizzle ) lets you quote the argument to the :not() selector as well as the :has() selector. To wit : $('div:not("span")') $('span:has("span")') In the Selectors standard , quotes are always representative of a string and never of a selector or a keyword, so quoting the argument to :not() is always invalid. This will not change in Selectors 4. You can also see that it's non-standard syntax by adding an unsupported CSS selector such as :nth-last-child(1) causing the selector to fail

I can't believe how hard this is to find, but even in the Google developer docs I can't find it. I need to be able to dynamically, only with JavaScript insert adsense. I also looked on StackOverflow and some others have asked this but no response. Hopefully this will be a better explanation and will get some replies. Basically, a user inserts my script, lets call it my.js (can't say what it is specifically at the moment.) my.js is loaded and in my.js some embedded media is displayed on their page then I need somehow to append the generated HTML from: <script type="text/javascript"><!-- google