jQuery Utilities Methods
Index
About This Index
This page is the jQuery Utilities index for the tutorial track. Each row links to a full guide with syntax, examples, and FAQs.
Learn the jQuery overview on /jquery. Use this page when you need a utility such as $.each(), $.extend(), or $.type().
Beginner path.
Start with $.each() and $.extend(), then $.map() / $.grep()—add the is* helpers when you need type guards.
Syntax
How to Call a Utility
Call utilities on $ / jQuery — they are not chained from a selection:
jQuery
$.each([1, 2, 3], function (i, value) {
console.log(i, value);
});
$.extend({}, { a: 1 }, { b: 2 }); // { a: 1, b: 2 }
$.map([1, 2, 3], function (n) { return n * 2; });
$.grep([1, 2, 3, 4], function (n) { return n % 2 === 0; });
$.type([]); // "array"
$.isPlainObject({}); // true
$.inArray("b", ["a", "b", "c"]); // 1Browse
jQuery Utilities Methods Table
All Utilities method guides in this jQuery tutorial series (35 tutorials).
Iteration & Filter
3 methodsWalk and transform collections — each, map, and grep.
Objects & Arrays
6 methodsMerge objects, combine arrays, convert array-likes, and search or dedupe.
| Method | Description | Tutorial |
|---|---|---|
$.extend() | Merge properties from one or more objects into a target — shallow or deep. | Try it |
$.merge() | Append elements from a second array-like onto the first — keeps duplicates. | Try it |
$.makeArray() | Convert NodeLists, jQuery collections, or arguments into a true array. | Try it |
$.inArray() | Search an array for a value and return its index, or -1 when not found. | Try it |
$.uniqueSort() | Remove duplicate DOM nodes and sort elements into document order. | Try it |
$.unique() | Legacy name for uniqueSort — deprecated since jQuery 3.0. | Try it |
Type Checking
8 methodsInspect JavaScript values with $.type and the is* helpers.
| Method | Description | Tutorial |
|---|---|---|
$.type() | Return an accurate lowercase type string for null, arrays, dates, and more. | Try it |
$.isArray() | Return true when a value is a genuine JavaScript array. | Try it |
$.isEmptyObject() | Return true when an object has no enumerable properties. | Try it |
$.isFunction() | Return true when a value is a JavaScript function. | Try it |
$.isNumeric() | Return true for finite numbers and numeric strings — reject NaN and Infinity. | Try it |
$.isPlainObject() | Return true for plain {} objects — not arrays or DOM nodes. | Try it |
$.isWindow() | Return true when a value is a browser window — deprecated in 3.3. | Try it |
$.isXMLDoc() | Return true when a DOM node is or belongs to an XML document. | Try it |
DOM & Data
6 methodsTest containment, store data, and parse HTML/XML strings.
| Method | Description | Tutorial |
|---|---|---|
$.contains() | Return true when a DOM element is a descendant of another. | Try it |
$.data() | Attach and retrieve arbitrary data on DOM elements via jQuery’s cache. | Try it |
$.removeData() | Delete one key or clear all jQuery data on a raw DOM element. | Try it |
$.parseHTML() | Parse an HTML string into an array of DOM nodes — scripts off by default. | Try it |
$.parseXML() | Parse a well-formed XML string into an XMLDocument. | Try it |
$.globalEval() | Execute JavaScript strings in the global scope — never pass untrusted input. | Try it |
Queues
2 methodsLow-level queue helpers — prefer .queue() / .dequeue() on elements day to day.
| Method | Description | Tutorial |
|---|---|---|
$.queue() | Show, add, or replace the function queue on a DOM element. | Try it |
$.dequeue() | Execute the next function on an element’s fx or custom queue. | Try it |
Helpers
6 methodsSmall utilities — trim, now, parseJSON, proxy, noop, and escapeSelector.
| Method | Description | Tutorial |
|---|---|---|
$.trim() | Remove leading and trailing whitespace — prefer String.prototype.trim(). | Try it |
$.now() | Return milliseconds since the Unix epoch — prefer Date.now() (deprecated 3.3). | Try it |
$.parseJSON() | Parse a JSON string into a value — prefer JSON.parse(). | Try it |
$.proxy() | Return a function with a fixed this — prefer Function.prototype.bind(). | Try it |
$.noop() | Return a shared empty function — placeholder for optional callbacks. | Try it |
$.escapeSelector() | Escape special characters in CSS selector strings for safe dynamic lookups. | Try it |
Legacy & Internals
4 methodsDeprecated or removed APIs — keep for migration notes only.
| Method | Description | Tutorial |
|---|---|---|
$.support | Internal browser capability flags — prefer Modernizr or native feature detection. | Try it |
$.browser | Removed user-agent flags — deprecated 1.3, removed 1.9; prefer feature detection or jQuery Migrate. | Try it |
$.error() | Throw an Error with the given message — used internally; prefer throw new Error() in app code. | Try it |
$.sub() | Create an isolated jQuery copy for plugins — removed in jQuery 1.9; prefer modules or noConflict. | Try it |
Frequently Asked Questions
Utilities are standalone helpers on the jQuery/$ object—not methods on a DOM selection. Use them to iterate ($.each), transform ($.map), merge ($.extend), and check types ($.type, $.isArray).
$.each(collection, fn) walks any array or object. $(sel).each(fn) only iterates elements in a jQuery DOM collection. Same idea, different targets.
Return false from the callback—similar to break in a for loop. Any other return continues to the next item.
Prefer native APIs in new code: String.prototype.trim() and JSON.parse(). The jQuery versions remain useful when reading older tutorials or supporting legacy browsers.
Start with $.each() and $.extend(), then $.map() / $.grep(). Learn the is* helpers when you need type guards.
Start with $.each()
Open the iteration guide—syntax, examples, and FAQs.
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