Learning jQuery(Fourth Edition)
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Accessing DOM elements

Every selector expression and most jQuery methods return a jQuery object. This is almost always what we want because of the implicit iteration and chaining capabilities that it affords.

Still, there may be points in our code when we need to access a DOM element directly. For example, we may need to make a resulting set of elements available to another JavaScript library, or we might need to access an element's tag name, which is available as a property of the DOM element. For these admittedly rare situations, jQuery provides the .get() method. To access the first DOM element referred to by a jQuery object, for example, we would use .get(0). So, if we want to know the tag name of an element with an ID of my-element, we would write:

varmyTag = $('#my-element').get(0).tagName;

For even greater convenience, jQuery provides a shorthand for .get(). Instead of writing the previous line, we can use square brackets immediately following the selector:

varmyTag = $('#my-element')[0].tagName;

It's no accident that this syntax appears to treat the jQuery object as an array of DOM elements; using the square brackets is like peeling away the jQuery layer to get at the node list, and including the index (in this case, 0) is like plucking out the DOM element itself.