10 Frequently Asked Questions About jQuery

Jquery FAQs

jQuery is a powerful resource for anyone who is interested in extending Javascript into something more powerful and more diverse on a website. From premade plugins to open-source code and script extensions, the jQuery database has an awful lot to offer to anyone interested in using it.

Although much of jQuery  prides itself on being user-friendly and accessible to a lot of people, there are still some ways that it deviates from standard Javascript and goes into more technical topics without much in the way of a tutorial. For that reason, this article is an overview of ten frequently asked questions about topics within jQuery that will, hopefully, set your mind at ease about using it.

What does $() mean?
The closed parentheses () after something in scripting terms signifies an object or a function. In simpler terms, $() is an alias, or something that stands in, for the function jQuery (). This might seem a little weird or unintuitive, and it might take a little while for you to get used to, but it’s often highly preferable to type $() rather than jQuery(). When you get a little more used to the way that it and jQuery work, you can use $() to abbreviate other items and then wrap them into a jQuery object. There are some advanced features, such as using $() to string together a selector string, but in general, $() is shorthand for jQuery().

What is the different between the ID selector and the class selector?Basic Selectors

The difference between ID and class selection is the same in jQuery as it is in other programs like CSS. An ID selector uses an object or element’s ID, appearing like something along the lines of, “#element1.” A class selector, meanwhile, uses a CSS class in order to select multiple elements at once. Obviously, then, if you want to select only one element, you’ll want to use an ID selector. If you want to select multiple elements, you’ll want to wrap them up into a CSS class, and then use a class selector to manipulate the CSS class that you’ve created.

Can you hide an image on a button click?
This question is often used in job interviews in order to test an applicant’s knowledge of jQuery and its associated codebase and systems. In particular, this question tests an applicant’s ability to solve a problem based on event handling, which jQuery offers a pretty good support base for. The code for it is simple and easy to figure out, since its based off the hide() event. The code for this task looks something like this: $(“#ButtonToClick”).click(function(){    $(“#ImageToHide”).hide(); });

Why use $(document).ready()?
Another very common question that’s asked in job interviews based around jQuery , this tests one’s knowledge of the ready() function, which is used to execute code when a document is ready for manipulation. This allows you to execute code after a DOM is fully loaded, such as when HTML has been parsed and the DOM tree has been constructed. What’s very useful about this function is that it works in all browsers and jQuery takes care of issues that might arise from it being a cross-browser project or database.

What is the difference between window.onload event and jQuery ready function?
This is a follow-up question to the last one, and the answer is quite simple. The Javascript onload function waits for the DOM to be created and it also waits for every available external resource to also load. This includes load-heavy items like images and video. The jQuery ready function, conversely, only waits for the DOM to be created, and then loads itself in tandem with everything else.

Learn Javascript And JQuery From Scratch

What is each () function and how do you use them?
In jQuery, () functions are functions that allow you to iterate them over a set of elements. For example, you could set up a function to pass over each() method, which will then execute itself from the jQuery object onto whatever other object has been called with the same tag.

What is the difference between $(this) and this keyword?
The answer to this question, which is also often asked during interviews, goes back to the first item we covered on this list. A keyword that is only this. will not access any jQuery functions, whereas a keyword written like $(this) will return as a jQuery object and will be related to any number of jQuery functions.

How can you retrieve an attribute of an HTML tag?
This is a question with another fairly simple answer. The way to retrieve an attribute from an HTML tag is to use the attr() command, which is linked to the HTML tag’s data. You simply use the attr() tag with the tag you want. An example of this can be seen here: $(“a”).each(function(){   alert($(this).attr(‘href’)); });

What is the difference between detach() and remove() method?
Detach() and remove() are both methods used to remove DOM elements. The main difference is that detach() keeps track of the last element that it was used to detach, so that it can be reattached later, and remove() only keeps a reference of it for future use, rather than the entire thing.

detach() and remove() method

What is the main advantage of loading jQuery library using CDN?
This is something we mentioned in a previous article. In general, using CDN to load jQuery is a good idea because a CDN doesn’t necessitate downloading the entirety of jQuery to function. Instead, you’re allowed to pick and choose what you’d like to have and take advantage of, rather than downloading the thing wholesale, which can be kind of a burden on your servers and memory capacity.

So there you have ten frequently asked questions, both about jQuery itself, and that someone interviewing for a position that makes heavy use of jQuery might be asked to reflect their knowledge of it.


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