JavaScript Node isSameNode() Method

What You’ll Learn

The Node.isSameNode() method is a legacy alias for ===: it asks whether two references point to the same node object. Learn how it differs from isEqualNode() and why MDN recommends === in new code.

Introduction

Identity answers: “Is this the exact node I stored earlier?” isSameNode() and === both answer that. Matching text or tags is not enough—two separate elements with the same content are still different objects.

MDN: there is no need to use isSameNode(); use the === strict equality operator instead. Learn the method so you can read older code, then write === in your own projects.

Understanding isSameNode()

MDN: a legacy alias for ===. It tests whether two nodes reference the same object.

• true — both sides are the identical node object.
• false — different objects (or not a matching node).
• Not about looks — identical markup can still be different nodes.
• New code — prefer nodeA === nodeB.

📝 Syntax

const same = node.isSameNode(otherNode);

// Preferred in new code:
const sameModern = node === otherNode;

Parameters

• otherNode — The node to test against. Required in the signature, but may be null.

Return value

A boolean: true if both are strictly the same object, otherwise false.

⚖️ isSameNode() / === vs isEqualNode()

Examples Gallery

Examples follow MDN Node.isSameNode() patterns and contrast identity with equality. Use View Output or Try It Yourself.

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

console.log(divList[0].isSameNode(divList[0])); // true
console.log(divList[0].isSameNode(divList[1])); // false
console.log(divList[0].isSameNode(divList[2])); // false

true
false
false

const a = document.getElementById("box");
const b = document.getElementById("box");
const c = document.getElementById("other");

console.log(a.isSameNode(b) === (a === b)); // true
console.log(a.isSameNode(c) === (a === c)); // true
console.log(a === b);                       // true

true
true
true

const divs = document.getElementsByTagName("div");
// divs[0] and divs[2] have the same text content

console.log(divs[0].isEqualNode(divs[2])); // true  (looks the same)
console.log(divs[0].isSameNode(divs[2]));  // false (different objects)
console.log(divs[0] === divs[2]);          // false

true
false
false

const original = document.getElementById("card");
const copy = original.cloneNode(true);

console.log(original.isSameNode(copy));  // false
console.log(original === copy);          // false
console.log(original.isEqualNode(copy)); // true

false
false
true

const el = document.getElementById("box");
const missing = document.getElementById("nope"); // null

console.log(el.isSameNode(null));    // false
console.log(el === null);            // false
console.log(el.isSameNode(missing)); // false

false
false
false

🚀 Common Use Cases

• Reading legacy code that still calls isSameNode.
• Teaching identity vs structural equality next to isEqualNode.
• Checking whether an event target is a stored button (=== preferred).
• Confirming two query results returned the same element instance.
• Avoiding the mistake of treating matching markup as the same node.

🔧 How It Works

📝 Notes

• Baseline Widely available (MDN, since August 2016).
• Not Deprecated, Experimental, or Non-standard — no status banner required.
• MDN: prefer ===; no need to call isSameNode() in new code.
• Related: lookupNamespaceURI(), isEqualNode(), cloneNode(), isDefaultNamespace(), JavaScript hub.

💡 Best Practices