Top jQuery Interview Questions and Answers for 2025 (Beginner to Advanced)

jQuery may not dominate modern front-end development the way it once did, but it still powers millions of websites and remains relevant in enterprise applications, legacy systems, WordPress themes and plugins, and rapid prototyping. If you are preparing for a jQuery interview, this guide covers commonly asked questions—from beginner concepts to more advanced techniques.

1. What is $() in the jQuery library?

The $() function is an alias for jQuery(). It looks unusual at first, but it keeps code short. $() wraps objects in a jQuery collection so you can chain jQuery methods. You can pass a selector string; jQuery returns a collection of matched DOM elements. Interviewers often use this question to quickly tell whether a candidate has real jQuery exposure.

2. What is $(document).ready()? Why use it?

ready() runs your code when the DOM is safe to manipulate—after HTML is parsed and the DOM tree is built. jQuery smooths over cross-browser differences. Compared to waiting for every image or asset, ready() fires earlier so behavior hooks in faster. You can register multiple ready callbacks; they run in document order.

3. JavaScript window.onload vs jQuery ready

window.onload waits for the full page load, including heavy images, audio, and video. If media is slow, code in onload runs late. jQuery’s $(document).ready() waits for the DOM only—not necessarily every image or external resource—so your logic often runs sooner. You can call ready() multiple times on one page; the classic onload handler pattern only accommodates a single assignment unless you chain logic manually. For DOM-centric work, ready() is usually the better default.

4. How do you find all selected options of a <select>?

For a multi-select, combine an attribute selector with :selected. Replace NameOfSelectedTag with your control’s name (or switch to an id selector).

$('[name=NameOfSelectedTag] :selected')

That returns only the selected option elements. You can target by id instead of name when it fits your markup.

5. What is each()? How do you use it?

each() iterates over the elements in a jQuery object—similar in spirit to iterators in other languages. You pass a callback that runs per element. Pair it with the :selected example to walk selected options (for example, showing each in an alert during a demo).

$('[name=NameOfSelectedTag] :selected').each(function () {
  alert($(this).text());
});

text() returns the visible text for each option. Inside each(), this is the raw DOM node; $(this) wraps it so you can call jQuery methods.

6. How do you add an HTML element to the DOM?

appendTo() inserts content at the end of a target element. You can move an existing node or append newly built markup—one of many DOM helpers jQuery provides.

7. Select all links that appear inside paragraphs

Use a descendant selector so only anchors nested under <p> match:

$('p a')

Equivalently: $('p').find('a'). Prefer the shortest selector that stays readable for your team.

8. $(this) vs this in jQuery

$(this) is a jQuery object—you can call .text(), .val(), .addClass(), and so on. this is the raw DOM element in the current callback context. You cannot invoke jQuery methods on this until you wrap it: $(this).

9. How do you read an attribute (for example href on links)?

Use attr() after selecting elements. Example: iterate anchors and read href (modern code often prefers prop() for intrinsic DOM properties—know both for interviews).

$("a").each(function () {
  alert($(this).attr("href"));
});

10. How do you set an attribute with jQuery?

attr() is overloaded: one argument reads the attribute; two arguments set it—attr(name, value). Example: $('img').attr('alt', 'Logo') updates or adds the alt text.