JavaScript Document applets Property

What You’ll Learn

Document.applets is a read-only deprecated instance property that once listed Java <applet> elements on a page. Today it always returns an empty HTMLCollection. Learn why applets disappeared, what legacy code looked like, and how to clean up obsolete detection scripts—with five examples and try-it labs.

Introduction

In the late 1990s and early 2000s, some websites embedded Java programs using the HTML <applet> tag. Scripts could enumerate them with document.applets, similar to how document.anchors listed named anchors.

That era is over. MDN notes that support for the <applet> element has been removed by all browsers, so document.applets always returns an empty collection now.

Related Document tutorials: anchors, all, Document constructor.

Understanding Document.applets

A read-only instance property on Document. Its value is an HTMLCollection. In historical browsers it listed every <applet> element; in modern engines the collection is always empty.

• Value — HTMLCollection (empty in all current browsers).
• Read-only — you do not assign a new collection to document.applets.
• Legacy purpose — enumerate embedded Java applets on a page.
• Modern reality — length is 0; no applets run.
• Indexed access — document.applets[i] is always undefined today.

📝 Syntax

document.applets

Value

An empty HTMLCollection in modern browsers (MDN).

Typical modern check

console.log(document.applets.length); // 0 — always empty today

⚖️ document.applets vs Related Legacy Collections

Examples Gallery

Examples follow MDN Document: applets. Use View Output or Try It Yourself for each case.

console.log(document.applets.length);
console.log(document.applets.length === 0); // true today

0
true

console.log(document.applets.constructor.name);
console.log(typeof document.applets.length); // "number"
console.log(document.applets.item(0));       // null

HTMLCollection
number
null

let count = 0;
for (const applet of document.applets) {
  count++;
  console.log(applet); // never reached today
}
console.log("applets found:", count);

applets found: 0

const queried = document.querySelectorAll("applet");
console.log("querySelectorAll:", queried.length);
console.log("document.applets:", document.applets.length);
console.log("both empty:", queried.length === 0 && document.applets.length === 0);

querySelectorAll: 0
document.applets: 0
both empty: true

// Legacy (remove):
// if (document.applets.length > 0) {
//   initJavaAppletBridge();
// }

// Modern: applets are unsupported — skip or show a message
function initInteractiveContent() {
  console.log("Using Canvas / WASM instead of applets");
}
initInteractiveContent();

Using Canvas / WASM instead of applets

🚀 Common Use Cases

• Reading legacy intranet pages — recognize applet enumeration scripts.
• Code archaeology — understand pre-HTML5 interactive content patterns.
• Migration audits — find and remove dead document.applets checks.
• Teaching web history — contrast plugins with open web standards.
• Not for new apps — never embed or query Java applets.
• Security reviews — flag remaining <applet> markup for removal.

📝 Notes

• document.applets is deprecated (MDN) — avoid in new code.
• Read-only property; returns an HTMLCollection, not a plain array.
• MDN: support for <applet> removed; collection always empty.
• No modern DOM replacement—the feature itself is obsolete.
• Do not confuse with document.embeds or document.plugins (also legacy).
• Related: anchors, ownerDocument, all.

💡 Best Practices