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JavaScript jQuery Basics (2014) Creating a Simple Lightbox Perform: Part 2

Posted by adammccann
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adammccann
Python Web Development Techdegree Student 12,554 Points

Why can't $('<div id="overlay"></div>') just be replaced with $('#overlay') ...?

I would've thought that $('#overlay') would be specific enough to grab the overlay element...I mean, that's what this bit of jQuery is doing, right? Grabbing the overlay element and assigning it to the $overlay variable?

3 Answers

Steven Parker
Steven Parker
231,275 Points
Steven Parker
Steven Parker
231,275 Points

The first one creates a new element, the second one selects an existing one.

When you write $('<div id="overlay"></div>') you are creating a new element which has the ID of "overlay". I would expect that in later code this element would be added to a document which did not have an element with that ID already.

On the other hand $('#overlay') will select an element that already exists in the document that has the ID of "overlay". Nothing new is created.

Sergey Blokhin
Sergey Blokhin
9,612 Points
Sergey Blokhin
Sergey Blokhin
9,612 Points

Why do we need to use $('')? can we create variable like this var $overlay = '<div id="overlay"></div>'; ?

Steven Parker
Steven Parker
231,275 Points
Steven Parker
Steven Parker
231,275 Points

Sure, but your new variable will contain an ordinary string, not a jQuery object. And the convention for naming variables is that you only start the name with a dollar sign ($) when it is used to hold jQuery objects, so that would not be "good practice" naming for a string variable.

Sergey Blokhin
Sergey Blokhin
9,612 Points
Sergey Blokhin
Sergey Blokhin
9,612 Points

Thank you Steven. Also what if I already have the <p></p> with a description for a photo. How do I take the text from it and assign it to overlay as a caption text?