Editing jQuery - "next" Loop vs "nextAll:first" This edit will create a new revision. Your details (optional) Name Email (won’t be displayed; might be used for Gravatar) URL Test case details Title * Published (uncheck if you want to fiddle around before making the page public) Description (in case you feel further explanation is needed)(Markdown syntax is allowed) Comparing the performance of finding the next sibling matching a given selector using `nextAll` with the `:first` pseudo-class vs. a naive `next` loop vs. a loop using a very, very slightly optimized version via `nextSibling`. Are you a spammer? (just answer the question) Preparation code Preparation code HTML (this will be inserted in the <body> of a valid HTML5 document in standards mode) (useful when testing DOM operations or including libraries) <script src="//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script> <script> (function($) { // Implementation for "naive next loop" function $.fn.nextMatchNaive = nextMatchNaive; function nextMatchNaive(selector) { var match; match = this.next(); while (match.length > 0 && !match.is(selector)) { match = match.next(); } return match; } // Implementation for "$(nextSibling) loop" // Really not much better than the naive one $.fn.nextMatchViaRaw = nextMatchViaRaw; function nextMatchViaRaw(selector) { var raw, match; raw = this[0]; if (!raw || !raw.nextSibling) { return $(); } raw = raw.nextSibling; while (raw && !(match = $(raw)).is(selector)) { raw = raw.nextSibling; } return raw ? match : $(); } // Prep the 10,000 divs var counter, div; for (counter = 1; counter <= 10000; ++counter) { div = document.createElement('div'); if (counter === 5000 || counter === 10000) { div.innerHTML = "This is #" + counter + " and has foo!"; div.className = "foo"; } else { div.innerHTML = "This is #" + counter; } document.body.appendChild(div); if (!window.firstDiv) { window.firstDiv = $(div); } } })(jQuery); </script> Include JavaScript libraries as follows: <script src="//cdn.ext/library.js"></script> Define setup for all tests (variables, functions, arrays or other objects that will be used in the tests) (runs before each clocked test loop, outside of the timed code region) (e.g. define local test variables, reset global variables, clear canvas, etc.) (see FAQ) Define teardown for all tests (runs after each clocked test loop, outside of the timed code region) (see FAQ) Code snippets to compare Test 1 Title Async (check if this is an asynchronous test) Code var foo = window.firstDiv.nextAll("div.foo:first"); if (foo.length !== 1 || foo[0].className !== "foo") { throw "Assertion failure: Didn't find div.foo"; } Test 2 Title Async (check if this is an asynchronous test) Code var foo = window.firstDiv.nextMatchNaive("div.foo"); if (foo.length !== 1 || foo[0].className !== "foo") { throw "Assertion failure: Didn't find div.foo"; } Test 3 Title Async (check if this is an asynchronous test) Code var foo = window.firstDiv.nextMatchViaRaw("div.foo"); if (foo.length !== 1 || foo[0].className !== "foo") { throw "Assertion failure: Didn't find div.foo"; } Test 4 Title Async (check if this is an asynchronous test) Code var foo = window.firstDiv.nextAll("div.foo").first(); if (foo.length !== 1 || foo[0].className !== "foo") { throw "Assertion failure: Didn't find div.foo"; }