JavaScript WorkerLocation hash Property

What You’ll Learn

The hash property of a WorkerLocation object returns the hash (fragment) part of the worker’s location. Learn self.location.hash, the string return value, how it differs from search and the page’s window.location.hash—with five examples and try-it labs.

Introduction

Inside a Web Worker, self.location is a WorkerLocation—the absolute URL of the script that worker is running. The hash property is the fragment after #, just like the familiar page API, but scoped to the worker script URL, not the HTML page.

MDN’s classic example: on a worker loaded from a URL ending in #examples, location.hash returns "#examples".

Understanding the hash Property

A read-only instance property on WorkerLocation that returns the hash part of the worker’s location as a string.

• Value — a string (includes leading # when a fragment exists).
• Empty fragment — "" when the worker URL has no hash.
• Access — self.location.hash or location.hash inside the worker.
• Workers only — not available on the main document thread.
• Baseline Widely available on MDN (since July 2015).

📝 Syntax

Read the property inside a worker script:

const result = location.hash;
// e.g. "#examples" when the worker URL ends with #examples

Value

A string.

Typical pattern (MDN idea)

// Inside a Web Worker whose URL includes #examples
const result = location.hash; // "#examples"
self.postMessage(result);

⚖️ hash vs Related Ideas

Examples Gallery

Examples follow MDN WorkerLocation.hash. Labs use blob workers and append #… to the worker URL so location.hash is easy to see.

// Worker URL: …blob:…#examples
const result = location.hash; // "#examples"
self.postMessage(result);

#examples

self.postMessage({
  hash: location.hash,
  isEmpty: location.hash === ""
});

hash: ""
isEmpty: true

self.postMessage({
  hash: location.hash,
  search: location.search,
  href: location.href
});

hash: #demo
search: (often "" for blob URLs)
href: blob:…#demo

// Main
const worker = new Worker(blobUrl + "#section-a");
worker.onmessage = (e) => console.log(e.data);

// Worker
self.postMessage(location.hash);

#section-a

const raw = location.hash;           // "#examples"
const id = raw.startsWith("#") ? raw.slice(1) : raw;
self.postMessage({ raw, id });

raw: #examples
id: examples

🚀 Common Use Cases

• Pass a mode or section id into a worker via the URL fragment.
• Log which fragment a shared worker script URL was started with.
• Branch worker startup based on location.hash.
• Debug blob-worker demos by tagging runs with #demo-1, #demo-2.
• Keep query params (search) and fragments (hash) separate in protocols.

🔧 How It Works

📝 Notes

• MDN: Baseline Widely available (since July 2015) — no Deprecated / Experimental / Non-standard banner.
• Only available in Web Workers (WorkerLocation / self.location).
• Read-only string; empty string when there is no fragment.
• Not the same object as window.location on the page.
• Related learning: Worker(), postMessage(), message.

💡 Best Practices