jQuery .is() Method

What Is .is()?

.is() (since jQuery 1.0) checks whether at least one element in the current set matches a selector, callback, jQuery object, or DOM element. It returns true or false — perfect for if checks and event handlers.

$("#box").is(".active")          // true / false
$(event.target).is("li")         // click was on an <li>?
$("input").parent().is("form")   // official parent check

// Since 1.6:
$el.is(function () { … })        // callback test
$el.is($other)                   // overlap with a jQuery set?
$el.is(domNode)                  // same DOM element?

// Not a filter — returns boolean, not a new set

How to Use .is()

Build a jQuery set, then ask a yes/no question about it.

1. Select elements ($("#box"), $(event.target), …).
2. Pass a selector, callback (1.6+), jQuery object, or DOM element.
3. Read the boolean — true if any element matches.
4. Branch with if — do not expect a chainable jQuery object.
5. In click handlers, test event.target to ignore child nodes.

Pseudocode

set = $(...)

function is(test):
    for each element in set:
        if element matches test:     // selector / callback / node
            return true
    return false

// Empty set → always false
// Never returns a new jQuery object

Cheat Sheet

Keep these facts handy while testing matches.

Live Preview

Pick a demo element and see common .is() checks — same idea as the official jQuery API examples.

Ready — choose an element and click Run .is().

jQuery Examples

Short, copy-ready snippets. Open DevTools, or use Try It Yourself for a live editor.

$("#out").text(
  "is .active? " + $("#box").is(".active") + "\n" +
  "is div? " + $("#box").is("div")
);

is .active? true
is div? true

$("ul").on("click", function (event) {
  var target = $(event.target);
  if (target.is("li")) {
    $("#out").text("Clicked li: " + target.text());
  } else {
    $("#out").text("Clicked a child — ignored");
  }
});

Clicked li: list item 2
— or —
Clicked a child — ignored

var isFormParent = $("input[type='checkbox']").parent().is("form");
$("#out").text("isFormParent = " + isFormParent);

isFormParent = true

var hasTwo = $("#item").is(function () {
  return $("strong", this).length === 2;
});
$("#out").text("Has two strong tags? " + hasTwo);

Has two strong tags? true

var $alt = $("#browsers li:nth-child(2n)");
var lines = [];
$("#browsers li").each(function () {
  lines.push($(this).text() + " → " + $(this).is($alt));
});
$("#out").text(lines.join("\n"));

Chrome → false
Safari → true
Firefox → false
Opera → true

Performance Notes

.is() can stop early once it finds a match. For hot paths, prefer simple selectors and small sets (for example $(event.target)).

Key Takeaways