Updated June 8, 2023
Introduction to jQuery Interview Questions and Answers
jQuery is a JavaScript library based on the principle “write less, do more.” It is fast, lightweight, and features rich. jQuery comes with easy-to-use APIs, which makes many tasks easier for UI development, like HTML document traversal and manipulation, event handling, and adding animation effects to a web page that works seamlessly across all web browsers. jQuery provides selectors that efficiently traverse the DOM tree of an HTML document’s structure. Ajax-based applications can build quickly and easily with jQuery. There are several inbuilt methods of jQuery, using which we can create animations and effects like sliding, showing or hiding elements, etc., with a single line of code.
You have finally found your dream job in jQuery but are wondering how to crack the interview and what could be the probable 2023 jQuery Interview Questions. Every interview is different, and the job scope is different too. Keeping this in mind, we have designed the most common jQuery Interview Questions and answers to help you get success in your interview.
Below is the most common feature of 2023 jQuery Interview Questions and Answers.
Part 1 – jQuery Interview Questions (Basic)
This first part covers basic Interview Questions and answers.
1. Define jQuery with its core features.
Answer:
jQuery is a fast and lightweight JavaScript library. It simplifies many tasks that consume a lot of time and effort with standard JavaScript. It facilitates rapid web development, Ajax interactions, event handling, animations, and HTML document traversing and manipulation. The central core features of jQuery are:
- DOM manipulation- You can easily traverse and modify DOM elements.
- Animations- Lots of built-in animations.
- AJAX- Assist a lot in developing responsive and feature-rich sites using AJAX.
- Lightweight- About 19kb in size.
- Event handling- You can easily capture several events with event handlers.
- Cross-browser support- Works well with IE 6.0+, Safari, Chrome and Opera, and Firefox.
2. What are the selectors in jQuery, and how many types are there?
Answer:
A jQuery selector is a function that uses the expression to find out matching elements from a DOM based on any given criteria. Once we select an element, we can perform certain operations on them. Basic selectors are:
1) Name: Select all elements that match the given element Name.
2). Class: Selects all elements that match the given Class.
3) #ID: Select a single element that matches the given ID.
4) Universal (*): Selects all elements in a DOM.
5) Attribute Selector: Select elements based on their attribute value.
3. What is the basic difference between the body? onload(), and document? ready() functions?
Answer:
Both functions differ from each other.
1) There may be multiple documents. On a single page, there is just one body and the ready () position. The onload() function is acceptable.
2) In contrast to the body, the ready() method is called when DOM is loaded for a page. When a page loads completely, including the DOM, images, and carrier-related resources, the onload() function is called.
4. What is the difference between $(this) and ‘this’ in jQuery?
Answer:
These are the common jQuery Interview Questions asked in an interview. Both reference the same element, but the difference is that “this” is used traditionally, but when “this” is used with $(), then it becomes a jQuery object on which we can use the functions of jQuery.
Example:
$(document).ready(function()
{
$('#clickme').click(function()
{
alert($(this).text());
alert(this.innerText);
});
});If you only use the “this” keyword, you can use the jQuery text() function to retrieve the text of the element because it is not a jQuery object. Once you wrap the “this” keyword in $(), you can use the jQuery function text() to retrieve the text of the element.
5. What are the various AJAX functions in jQuery?
Answer:
Ajax call allows the user to exchange data with a server and update parts of a page without reloading the entire page. Some of the functions of AJAX are as follow:
1. $.ajax(): It is considered to be the lowest level and basic functions. It is used to send requests. This function can be performed without a selector.
2. $.ajaxSetup(): This function is used to define and set the options for various Ajax calls.
For example:
$.ajaxSetup({
"type":"POST",
"url":"ajax.php",
"success":function(data)
{
$("#bar")
.css("background","yellow")
.html(data);
}
});3. Shorthand Ajax methods: They comprise simply the wrapper function that call $.ajax() with certain parameters already set.
4. $.getJSON(): This is a special type of shorthand function that is used to accept the URL to which the requests are sent. Also, optional data and optional callback functions are possible in such functions.
Part 2 – jQuery Interview Questions (Advanced)
This first part covers Advanced Interview Questions and answers
6. What is JQuery.noConflict?
Answer:
jQuery provides the option of no conflict to overcome conflicts between different JS frameworks or libraries. When we use jQuery’s no-conflict mode, we replace the $ with a new variable and assign some other JavaScript libraries to jQuery. Also, use the $ as jQuery’s function or variable name. And in our development life, we are not strict with only jQuery.
Code:
jQuery.noConflict();
jQuery(document).ready(function(){
jQuery("div").hide();
});We can also use your own specific character in place of the $ sign in jQuery.
var $j = jQuery.noConflict();
$j(document).ready(function(){
$j("div").hide();
});7. What is the use of the jQuery .each() function?
Answer:
It is a general function that will loop through a collection. You can iterate through Array-like objects with a length property using their index position and value. You can iterate through other objects using key-value properties. This function, however, works differently from the $(selector).each() function that works on the DOM element using the selector. But both iterate over a jQuery object.
The callback function can receive two arguments when we send an object that resembles an array to the.each() function: the index of the item and the value of the current array.
Example:
$("button").click(function(){
$("li").each(function(){
alert($(this).text())
});
});Let us move to the next jQuery Interview Questions.
8. What are the methods used to provide effects in jQuery?
Answer:
jQuery provides many wonderful effects; we can apply these effects with a simple configuration. The effect may be hiding, showing, toggling, fadeout, fade in, fade to, and so on toggle(), Show(), and hide() methods. Similarly, we can use other methods as in the following:
- animate ( params, [duration, easing, callback] ) This function makes custom animations for your HTML elements.
- fadeIn ( speed [callback] ) This function fades in all the matched elements by adjusting their opacity and firing an optional callback after completion.
- fadeOut ( speed, [callback] ) This function is used to fade out all the matched elements by adjusting their opacity to 0, then setting the display to “none” and firing an optional callback after completion.
- fadeTo ( speed, opacity, callback ) This function fades the opacity of all the matched elements to a specified opacity and fires an optional callback after completion.
- stop ( [clearQueue, goto end ] ) This function stops all the currently running animations.
9. Which one is faster, document.getElementByID (‘txtName’) or $ (‘#txtName’).?
Answer:
This is one of the most common jQuery interview questions. The “$(‘#txtName’)” jQuery method to pick txtName internally calls document.getElementByID(‘txtName’).
10. What is the difference between $ (‘div’) and $ (‘<div/>’) in jQuery?
Answer:
$(‘<div/>’): This creates a new div element.
While $(‘div’) picks all of the div elements on the page, this is not added to the DOM tree until we don’t append it to any DOM elements.
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