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

Steve Fan
Steve Fan
8,218 Points
Posted by Steve Fan
Steve Fan
8,218 Points

Why we need to use $('<div id="overlay"></div>') but not '<div id="overlay"></div>'.

In the video, the instructor set: var overlay = $('<div id="overlay"></div>');

But what we need to fill in the "append()" is: '<div id="overlay"></div>'

So why he use $('<div id="overlay"></div>') but not '<div id="overlay"></div>'

And what $() really do in this command?

Could someone help me to explain this please.

1 Answer

Seth Kroger
Seth Kroger
56,414 Points
Seth Kroger
Seth Kroger
56,414 Points

append() can take a variety of arguments, including string, HTMLand jQuery object. $('<div id="overlay"></div>') turns the HTML into a jQuery object. I'd have to check the code for the project to be certain, but I'm fairly sure you'll be using overlay again later in the code and that's why it's stored in a variable/jQuery object.

Steve Fan
Steve Fan
8,218 Points
Steve Fan
Steve Fan
8,218 Points

Thanks, Seth K. I get it now. Could I ask you one more question? Why we cannot use normal variables such as "overlay" or "image" But we have to use jQuery objects such as "$overlay", "$image" all the time?

Is there any advantage when using jQuery objects?

Seth Kroger
Seth Kroger
56,414 Points
Seth Kroger
Seth Kroger
56,414 Points

Beginning a variable name with "$" when it's supposed to be a jQuery object is just a stylistic convention and doesn't necessarily have to be followed.

Steve Fan
Steve Fan
8,218 Points
Steve Fan
Steve Fan
8,218 Points

So you mean we also can just leave the variables alone and use it like normal. Everything still stay the same, isn't it?

Steve Fan
Steve Fan
8,218 Points
Steve Fan
Steve Fan
8,218 Points

I just checked it. Without $, when I try to run the webpages, It noticed something in console like: overlay.append(image); is not a function //I took off all $ in the js file

I doubt that $ have to be appear all the time or I just get lost?