"Exploring the world of JavaScript variables and selecting elements through the

I have a question regarding DOM selectors.

Is there a difference in performance between the following two code blocks:

First Code Block:

if (document.getElementById("post-dropdown-menu-" + postID) && document.getElementById("post-dropdown-menu-" + postID).style.display != "none") {
            document.getElementById("post-dropdown-menu-" + postID).fadeOut(200);
            return false;
}

Second Code Block:

var neededElement = document.getElementById("post-dropdown-menu-" + postID);

if (neededElement && neededElement.style.display != "none") {
            neededElement.fadeOut(200);
            return false;
}

I am curious to know if browsers or JavaScript will reprocess the DOM selection if an element is already being used within a function.

javascript

Answer №1

Definitely, the second option proves to be quicker since it involves just one query selector, leading to faster processing.

Here is a performance test conducted using JSBench.

https://i.sstatic.net/yzvgt.png

It's important to note that the difference may not be noticeable unless you are utilizing this within a loop or similar scenario.

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