JQuery interview questions and Answers
jQuery is a feature-rich, lightweight, and fast JavaScript library, which makes HTML documents, event handling, Ajax, and animation easier with a simple API that works across almost all browsers. These jQuery interview questions will enhance your skills and help you to write in a mainstream JavaScript library, used by major players. The critical purpose of jQuery is to make using JavaScript more convenient on your website. A great combination of extensibility and flexibility, jQuery takes a lot of general tasks that require multiple lines of JavaScript code and wraps them in a manner that you can use with a single line of code.
Most Frequently Asked JQuery interview questions
This is used mostly to return a jQuery object in the code. It can also check if an object exists or not.
AJAX is a descriptor for Asynchronous XML and JavaScript. It is a group of technologies which work together to give dynamic behavior. It means users can enter data on a web form, and without refreshing the entire page, data can be sent to the server or loaded from server to browser. AJAX is used to load google map.
jQuery effect methods are used to create custom animation effects on websites.
For example, few of the effects methods available in jQuery are:
- animate()
- delay()
- clearQueuue()
- fadeIn()
- fadeout()
- dequeue()
- fadeTo()
- fadeToggle()
$(window).load is provided by the browser to show that all assets on the page (like images, videos) are loaded. So if any calculation or user of assets is needed in the code it should happen after $(window).load is done.
$(document).ready is used for DOM object tree loading. This means that we can be sure that DOM object is ready. Note DOM is loaded before page. So if you are trying to execute any code which uses page assets, it may fail.
In jQuery, the size or size() methods return the number of elements in the object. The .length does the same activity, but faster compared to size method as it’s a property and size is a method with an overhead functional call.
jQuery is a client scripting language.
The element selector in jQuery is used to select multiple elements.
Its syntax is $('element1, element2, element 3,....").
The selection elements need to be specified and then with the help of * elements can be selected in any document.
Developers can use this.title function inside the function to get the attribute of an HTML tag in jQuery. Use the following script:
$('a').click(function() {
var myTitle = $(this).attr ( "title" ); // from jQuery object
//var myTitle = this.title; //javascript object
alert(myTitle);
});
jQuery comes with two syntaxes, addClass()and,removeClass() to respectively add or remove CSS classes dynamically.
These can be used with the following syntax forms:
$(‘#para1’).addClass(‘highlight’);$(‘#para1’).removeClass(‘highlight’);
The document.getElementbyId( "ourID") is faster because it calls the JavaScript engine directly. jQuery is a wrapper that standardizes DOM control such that it works reliably in each significant browser. A jQuery object is built by the $ sign, and it will first parse the selector as jQuery can search things via attribute, class, etc. The document.getElementbyId can only find the elements by the id.
A jQuery object is actually not a native object so it takes time to create one and it additionally has considerably more potential.
Development History of jQuery
jQuery was released by John Resig at the BarCamp NYC in January 2006. Currently, it is headed by Timmy Wilson and managed by a team of expert developers.
Latest Version: The most recent version is 3.5.0, which was released on 4th May 2020.
Advantages
- Easy to learn and intuitive
- Deals with many cross-browser bugs
- Clean and simple syntax
- Open source library
- Highly extensible
These jQuery interview questions will help you prepare for your upcoming job interview as well and fast-track your career, whether you are a fresher or an experienced Jquery developer.