JavaScript Node isSameNode() Method

What Is isSameNode()?

node.isSameNode(otherNode) returns true when both values refer to the exact same node object. MDN calls it a legacy alias for === (MDN).

a.isSameNode(b)  ≡  a === b
→ true  if same object
→ false if different objects — or if b is null

a === b              → same object?  (prefer this)
a.isSameNode(b)      → same object?  (legacy alias)
a.isEqualNode(b)     → equal structure?

How to Use isSameNode()

Pass another node (or null) and read the boolean — or just use ===.

1. Get two node references to compare.
2. Prefer a === b for identity (MDN).
3. Or call a.isSameNode(b) — same result as ===.
4. Use isEqualNode when you care about structure, not identity.

Pseudocode

// isSameNode is a legacy alias for ===
return a === otherNode

// which means:
if a and otherNode are the exact same object:
    return true
else:
    return false   // includes otherNode === null

Cheat Sheet

Keep these identity facts handy.

Live Preview

Compare three divs (MDN-style): matching content is not the same object.

Choose a pair, then Compare…

JavaScript Examples

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

const divs = document.getElementsByTagName("div");

console.log(divs[0].isSameNode(divs[0])); // true
console.log(divs[0].isSameNode(divs[1])); // false
console.log(divs[0].isSameNode(divs[2])); // false (same text, different node)

true
false
false

const a = document.getElementById("card");
const b = document.getElementById("card");

console.log(a.isSameNode(b)); // true
console.log(a === b);         // true
console.log(a.isEqualNode(a.cloneNode(true))); // true (structure)
console.log(a.isSameNode(a.cloneNode(true)));  // false (new object)

true
true
true
false

const el = document.createElement("div");

console.log(el === el);             // true  ← prefer this
console.log(el.isSameNode(el));     // true  (legacy alias)
console.log(el.isSameNode(null));   // false
console.log(el === null);           // false

true
true
false
false

Performance Notes

Identity is a reference check — use it in hot paths. Reach for isEqualNode only when structure matters.

Key Takeaways