What is the reason behind using an index of 0 in the following code?
var $one = $('#one')[0];
Is there a specific purpose for not just using var $one = $('#one'); ?
SOURCE
I came across the above code while researching about jQuery, how to use multiple cached elements
They are not the same.
let $element = $('#one')[0];
This code caches the first DOM node that matches the selector #one. If you want to use jQuery functions on it, you would need to convert it back to a jQuery object like this: $($element), and then you can use methods like $($element).addClass("example");.
let $element = $('#one');
This code caches the jQuery object itself, allowing you to simply call: $element.addClass("example");
The choice between these two options depends on the specific requirements for the $element variable and how it will be used.
Here is a jsFiddle link with the above examples.
let element = $('#one')[0]; retrieves the specific DOM element.
let $element = $('#one'); gives back the jQuery object that wraps around the element.
The reason for this is that `$('#one')` represents a jQuery object, which is essentially an object that behaves like an array containing the specified element. By adding `[0]`, you are retrieving the first and only element within that jQuery object.
In terms of optimization, when you work with selectors in jQuery (or Sizzle), it searches through the DOM to find that specific element every time you use `$('#one')`. This can be resource-intensive if done repeatedly.
$('#one')
Instead of constantly searching the DOM, it's more efficient to cache the DOM element. You can easily recreate jQuery objects by referencing existing elements, which doesn't add much overhead compared to repeatedly searching the DOM.
var one = $('#one')[0]
// or alternatively
var one = document.getElementById('one');
// Now, instead of searching through the DOM each time,
// jQuery uses this cached reference.
var theOne = $(one);
// Another jQuery object using the same "one" element retrieved earlier
var anotherOne = $(one);
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