jQuery unique() Method

What Is unique()?

jQuery.unique(array) (alias $.unique) sorts an array of DOM elements in place, removes duplicate node references, and returns that array in document order (added in jQuery 1.1.3). Since jQuery 3.0 it is only an alias of $.uniqueSort().

$.unique(domArray)  → same array, sorted + deduped

// Duplicate = same node object (identity), not same HTML
// DOM elements only — not strings or numbers

// Modern name (same function in jQuery 3+):
$.uniqueSort(domArray)

How to Use unique()

Collect DOM nodes into a plain array, then unique (or uniqueSort) them.

1. Build a plain array of DOM elements (.get() / .toArray()).
2. Optionally merge arrays with $.merge or concat.
3. Call $.unique(arr) — or $.uniqueSort(arr) in new code.
4. Use the same array afterward (it is mutated in place).

Pseudocode

function unique(array):
    // DOM elements only
    sort array into document order
    remove entries that are the same node object
    return array   // mutated in place

// Typical flow:
nodes = $("div").get()
$.merge(nodes, $(".dup").get())
$.unique(nodes)          // or $.uniqueSort(nodes)

Cheat Sheet

Keep these facts handy while reading legacy jQuery code.

Live Preview

Pick a sample node list, run $.unique, and inspect length / order.

sample = Same node 3×
before → 3
after  → 1

jQuery Examples

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

var target = document.getElementById("panel");
var nodes = [target, target, target];

console.log(nodes.length);  // 3
$.unique(nodes);
console.log(nodes.length);  // 1

3
1

var items = $("li.item").get();  // three different <li> nodes

console.log(items.length);  // 3
$.unique(items);
console.log(items.length);  // 3  (still three nodes)

3
3

var nodes = [
  document.querySelector("#third"),
  document.querySelector("#first"),
  document.querySelector("#second")
];

$.unique(nodes);

console.log(nodes.map(function (el) { return el.id; }).join(" → "));
// "first → second → third"

first → second → third

var a = $("nav a").get();
$.merge(a, $(".footer-link").get());
$.unique(a);

var b = $("nav a").get();
$.merge(b, $(".footer-link").get());
$.uniqueSort(b);

console.log(a.length === b.length);  // true
// Prefer $.uniqueSort in new code

true

Performance Notes

You rarely need this in application code — jQuery uses it internally. When you do, run it once after merging node arrays, not on every click.

Key Takeaways