The use of ``++find++`` allows ``++document.getElementById()++`` to be used for the top-level selection, and saves the jQuery Sizzle engine for where it's really needed. That makes the query faster, and your application more responsive.
From the jQuery documentation:
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Beginning your selector with an ID is always best.
The ``++.find()++`` approach is faster because the first selection is handled without going through the Sizzle selector engine – ID-only selections are handled using ``++document.getElementById()++``, which is extremely fast because it is native to the browser.
var $productIds = $("#products").find("div.id"); // Compliant - #products is already selected by document.getElementById() so only div.id needs to go through Sizzle selector engine