Top 7 JQuery Interview Questions & Answers in 2020 [For Freshers & Experienced]

With the rise of the digital world, more and more companies are preferring online modes of operation. To operate digitally, most of the companies need a digital platform to work on. They build websites where they can showcase their work, collaborate, and maintain different workflows. 

A company must have a website that attracts the user and eases their experience with the website. A website can also reflect the company’s theme or brand and make the customer more aware of them. For this purpose, companies hire web developers who help them in building smooth and beautiful websites. 

HTML (HyperText Markup Language) is one of the most basic languages used to design any website’s underlying code. On top of it, multiple languages like JavaScript are used for further animations and beautification. To interact with HTML, JavaScript has a certain set of tools or libraries. One of the famous libraries is JQuery. 

JQuery is designed to beautify the HTML DOM tree traversal and manipulation. It is also very handy in Ajax, event handling, and animations in CSS. It is free to use and open-source and is used by around 75% of the most popular websites. Due to this fact, most of the companies require professionals to work with JQuery.

In this article, we will list out important JQuery interview questions and answers.

jquery interview questions

Source

JQuery is one of the top 10 skills that Javascript developers should learn.

Read: HTML Developer Salary in India: For Freshers & Experienced

1. What do you know about JQuery connect?

It is a plugin that binds or connects a function with another function. Whenever a function from another object is executed, it tries to execute that particular function. It is more like a handler for a different function. It can connect a function to a DOM object. 

Sample Code- 

$.connect(object1, ‘test1’, object1, test2); 

In this code, the test 2 function of object 2 is bound to the test 1 function of object 1. Hence, the test 2 function will also be executed whenever the test 1 function is executed.

2. List out some advantages of JQuery

Some of the major advantages of JQuery over others are- 

  1. Since it is just like an extension of JavaScript, there is no need to learn a new syntax.
  2. It keeps the code simple, reusable, and clear.
  3. It is supported by most of the browsers. Hence, the developer need not worry about the specific needs of different browsers.
  4. The code complexity is generally very low because heavy loops involving DOM are avoided.
  5. It has an excellent in house event detection and handling.
  6. It is supported by many plug-ins that easily cater to different kinds of needs of the client.

3. What are JQuery filters? 

Filters are used to fetch certain elements that satisfy the specified demands. You can define a specific criterion using the filter method and impose it on DOM elements. It works like the search function that simply eliminates the results that are not needed.

A sample implementation of filters in the JQuery filter. 

A sample implementation of filters in the JQuery filter.

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4. Enlist the jQuery methods that you use to provide effects

Some of the major effects based jQuery methods are:

  1. To run custom animation on the selected items, we use the animate () method.
  2. To set a delay time for the queue of functions that will work on the selected items, we use the delay () method.
  3. To simply show the selected items, we use show () method.
  4. To simply stop the current animation on the selected items, we use stop () method.
  5. To simply hide the selected items, hide () function is used.
  6. fadeIn() method is used to fade in the selected items.
  7. fadeOut() method is used to fade out the selected items.
  8. If we want to toggle the animation between the show () and hide () methods, we use the toggle () method.

5. Tell me something about different types of filters in JQuery

There are many methods that can be used to filter in JQuery. 

The major ones are- 

  1. Filter () method: It simply takes a function and an expression as arguments. It filters the expression according to the specified elements and outputs the specific element that satisfies the filter. 
  2. First () method: It is used to return the first element from a bundle of elements that have matched the filter’s criteria.
  3. Last (): It is just like the opposite of the first () method. It is used to output the last element from a bundle of elements that have matched the criteria of the filter.
  4. Eq (): To select the elements from a bundle of elements that have matched the filter criteria and return the specific elements with the dedicated index number.
  5. Has (): It is used to select the elements from a bundle of elements that have matched the filter’s criteria and output the element with the required descendant element.
  6. Not (): To select the elements from a bundle of elements that have matched the filter criteria and output the elements that don’t match the required condition, we use not () method.
  7. The slice () method is used to select the elements from a bundle of elements that have matched the filter’s criteria specified by the range of indices.

Read: Javascript Interview Questions & Answers

6. What are some of the slide effects available in JQuery?

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A total of 3 different sliding methods are there in jQuery:

SlideDown() : To slideDown an element.

Sample Code-

$(selector).slideDown(speed,callback); 

The duration of the slideDown effect is defined in the speed parameter. For example, “slow,” “fast,” or in milliseconds. The callback function is optional. It is usually executed post the completion of the slideDown animation on the specified element.

SlideUp() : To slide up an element. It is just the opposite of the SlideUp() method.

Sample Code- 

$(selector).slideUp(speed,callback); 

The duration of the slideDown effect is defined in the speed parameter. For example, “slow,” “fast,” or in milliseconds. The callback function is optional. It is usually executed post the completion of the slideDown animation on the specified element.

SlideToggle(): To toggle between the slideUp() and slideDown() method. In case an element has been executed with slide up, this method will slide them up and vice versa.

Sample code-

$(selector).slideToggle(speed,callback); 

The duration of the slideDown effect is defined in the speed parameter. For example, “slow,” “fast,” or in milliseconds. The callback function is optional. It is usually executed post the completion of the slideDown animation on the specified element.

7. Tell me the contrast between JQuery.size() and JQuery.length.

To output the total number of elements in the object, we use the JQuery .size() method. JQuery also provides the .length property for the elements, which more or less does the same task, but with a small difference. The .length property does not have the overhead of a function call. Due to this fact, .length is preferred generally over .size() to avoid any potential errors.

Also Read: JavaScript vs JQuery: Difference Between JavaScript and JQuery

Conclusion

Although we have covered the majority types of JQuery interview questions and answers, this is not an exhaustive list. Before going for an interview, it is highly recommended that the candidate should have an in-depth understanding of all these concepts and some hands-on experience.

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