JavaScript NodeList keys() Method

What You’ll Learn

The keys() method of a NodeList returns an iterator of indexes (unsigned integers). Learn for...of over list.keys(), how it differs from entries() and values(), and how to pair keys with item()—with five examples and try-it labs.

Introduction

A NodeList is ordered. Each node has a position: index 0, 1, 2, and so on. list.keys() gives you an iterator over those index numbers—not the nodes themselves.

MDN’s classic idea: on a list of three child nodes, for (const key of list.keys()) logs 0, then 1, then 2.

Understanding the keys() Method

An instance method on NodeList that returns an iterator over all keys in the list. The keys are unsigned integers (zero-based indexes).

• Returns — an iterator (not an array).
• Each step — a number: 0, 1, 2, …
• Parameters — none.
• Does not mutate the NodeList or the DOM by itself.
• Baseline Widely available on MDN (since October 2017).

📝 Syntax

Call the method on a NodeList:

keys()

Parameters

None.

Return value

An iterator. Each yielded value is an unsigned integer index.

Typical pattern (MDN idea)

const list = node.childNodes;

for (const key of list.keys()) {
  console.log(key);
  // 0, 1, 2
}

⚖️ keys() vs Related Ideas

Examples Gallery

Examples follow MDN NodeList.keys(). Labs use childNodes and querySelectorAll.

const node = document.createElement("div");
node.appendChild(document.createElement("p"));
node.appendChild(document.createTextNode("hey"));
node.appendChild(document.createElement("span"));

const list = node.childNodes;

for (const key of list.keys()) {
  console.log(key);
}

0
1
2

for (const key of list.keys()) {
  const node = list.item(key);
  console.log(key, node.nodeName);
}

0 P
1 #text
2 SPAN

const items = document.querySelectorAll("li");

for (const key of items.keys()) {
  console.log(key, items[key].textContent);
}

0 Apple
1 Banana
2 Cherry

const indexes = Array.from(list.keys());
console.log(indexes);
// [0, 1, 2]

[0, 1, 2]

for (const key of list.keys()) {
  console.log("key", key);
}

for (const [index, node] of list.entries()) {
  console.log("entry", index, node.nodeName);
}

key 0
key 1
key 2
entry 0 P
entry 1 #text
entry 2 SPAN

🚀 Common Use Cases

• Walk indexes with for...of and early break.
• Pair keys with item() to resolve nodes by index.
• Build an array of indexes with Array.from.
• Teach iterator methods alongside Array keys().
• Compare index-only iteration with entries() and values().

🔧 How It Works

📝 Notes

• MDN: Baseline Widely available (since October 2017) — no Deprecated / Experimental / Non-standard banner.
• Returns an iterator; yields indexes, not nodes.
• Indexes are zero-based unsigned integers.
• Does not mutate the DOM by itself.
• Related learning: entries(), item(), forEach(), childNodes.

💡 Best Practices